MINOR: fix warnings in Kafka Streams state store tests (#17855)

Reviewers: Chia-Ping Tsai <chia7712@gmail.com>

streams/src/test/java/org/apache/kafka/streams/kstream/internals/SessionWindowedKStreamImplTest.java

@@ -227,7 +227,7 @@ public class SessionWindowedKStreamImplTest {
         try (final TopologyTestDriver driver = new TopologyTestDriver(builder.build(), props)) {
             processData(driver);
             final SessionStore<String, Long> store = driver.getSessionStore("count-store");
-            final List<KeyValue<Windowed<String>, Long>> data = StreamsTestUtils.toList(store.fetch("1", "2"));
+            final List<KeyValue<Windowed<String>, Long>> data = StreamsTestUtils.toListAndCloseIterator(store.fetch("1", "2"));
             if (!emitFinal) {
                 assertThat(
                         data,
@@ -255,7 +255,7 @@ public class SessionWindowedKStreamImplTest {
         try (final TopologyTestDriver driver = new TopologyTestDriver(builder.build(), props)) {
             processData(driver);
             final SessionStore<String, String> sessionStore = driver.getSessionStore("reduced");
-            final List<KeyValue<Windowed<String>, String>> data = StreamsTestUtils.toList(sessionStore.fetch("1", "2"));
+            final List<KeyValue<Windowed<String>, String>> data = StreamsTestUtils.toListAndCloseIterator(sessionStore.fetch("1", "2"));
 
             if (!emitFinal) {
                 assertThat(
@@ -288,7 +288,7 @@ public class SessionWindowedKStreamImplTest {
         try (final TopologyTestDriver driver = new TopologyTestDriver(builder.build(), props)) {
             processData(driver);
             final SessionStore<String, String> sessionStore = driver.getSessionStore("aggregated");
-            final List<KeyValue<Windowed<String>, String>> data = StreamsTestUtils.toList(sessionStore.fetch("1", "2"));
+            final List<KeyValue<Windowed<String>, String>> data = StreamsTestUtils.toListAndCloseIterator(sessionStore.fetch("1", "2"));
             if (!emitFinal) {
                 assertThat(
                         data,

streams/src/test/java/org/apache/kafka/streams/kstream/internals/SlidingWindowedKStreamImplTest.java

@@ -208,7 +208,7 @@ public class SlidingWindowedKStreamImplTest {
             {
                 final WindowStore<String, Long> windowStore = driver.getWindowStore("count-store");
                 final List<KeyValue<Windowed<String>, Long>> data =
-                    StreamsTestUtils.toList(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
+                    StreamsTestUtils.toListAndCloseIterator(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
 
                 assertThat(data, equalTo(Arrays.asList(
                     KeyValue.pair(new Windowed<>("1", new TimeWindow(0, 100)), 1L),
@@ -223,7 +223,7 @@ public class SlidingWindowedKStreamImplTest {
                 final WindowStore<String, ValueAndTimestamp<Long>> windowStore =
                     driver.getTimestampedWindowStore("count-store");
                 final List<KeyValue<Windowed<String>, ValueAndTimestamp<Long>>> data =
-                    StreamsTestUtils.toList(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
+                    StreamsTestUtils.toListAndCloseIterator(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
                 assertThat(data, equalTo(Arrays.asList(
                     KeyValue.pair(new Windowed<>("1", new TimeWindow(0, 100)), ValueAndTimestamp.make(1L, 100L)),
                     KeyValue.pair(new Windowed<>("1", new TimeWindow(50, 150)), ValueAndTimestamp.make(2L, 150L)),
@@ -248,7 +248,7 @@ public class SlidingWindowedKStreamImplTest {
             {
                 final WindowStore<String, String> windowStore = driver.getWindowStore("reduced");
                 final List<KeyValue<Windowed<String>, String>> data =
-                    StreamsTestUtils.toList(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
+                    StreamsTestUtils.toListAndCloseIterator(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
                 assertThat(data, equalTo(Arrays.asList(
                     KeyValue.pair(new Windowed<>("1", new TimeWindow(0, 100)), "1"),
                     KeyValue.pair(new Windowed<>("1", new TimeWindow(50, 150)), "1+2"),
@@ -262,7 +262,7 @@ public class SlidingWindowedKStreamImplTest {
                 final WindowStore<String, ValueAndTimestamp<Long>> windowStore =
                     driver.getTimestampedWindowStore("reduced");
                 final List<KeyValue<Windowed<String>, ValueAndTimestamp<Long>>> data =
-                    StreamsTestUtils.toList(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
+                    StreamsTestUtils.toListAndCloseIterator(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
                 assertThat(data, equalTo(Arrays.asList(
                     KeyValue.pair(new Windowed<>("1", new TimeWindow(0, 100)), ValueAndTimestamp.make("1", 100L)),
                     KeyValue.pair(new Windowed<>("1", new TimeWindow(50, 150)), ValueAndTimestamp.make("1+2", 150L)),
@@ -289,7 +289,7 @@ public class SlidingWindowedKStreamImplTest {
             {
                 final WindowStore<String, String> windowStore = driver.getWindowStore("aggregated");
                 final List<KeyValue<Windowed<String>, String>> data =
-                    StreamsTestUtils.toList(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
+                    StreamsTestUtils.toListAndCloseIterator(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
                 assertThat(data, equalTo(Arrays.asList(
                     KeyValue.pair(new Windowed<>("1", new TimeWindow(0, 100)), "0+1"),
                     KeyValue.pair(new Windowed<>("1", new TimeWindow(50, 150)), "0+1+2"),
@@ -303,7 +303,7 @@ public class SlidingWindowedKStreamImplTest {
                 final WindowStore<String, ValueAndTimestamp<Long>> windowStore =
                     driver.getTimestampedWindowStore("aggregated");
                 final List<KeyValue<Windowed<String>, ValueAndTimestamp<Long>>> data =
-                    StreamsTestUtils.toList(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
+                    StreamsTestUtils.toListAndCloseIterator(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
                 assertThat(data, equalTo(Arrays.asList(
                     KeyValue.pair(new Windowed<>("1", new TimeWindow(0, 100)), ValueAndTimestamp.make("0+1", 100L)),
                     KeyValue.pair(new Windowed<>("1", new TimeWindow(50, 150)), ValueAndTimestamp.make("0+1+2", 150L)),
@@ -410,7 +410,7 @@ public class SlidingWindowedKStreamImplTest {
             {
                 final WindowStore<String, String> windowStore = driver.getWindowStore("aggregated");
                 final List<KeyValue<Windowed<String>, String>> data =
-                    StreamsTestUtils.toList(windowStore.fetch("1", "1", ofEpochMilli(0), ofEpochMilli(10000L)));
+                    StreamsTestUtils.toListAndCloseIterator(windowStore.fetch("1", "1", ofEpochMilli(0), ofEpochMilli(10000L)));
                 assertThat(data, equalTo(Arrays.asList(
                     KeyValue.pair(new Windowed<>("1", new TimeWindow(900, 1000)), "0+4"),
                     KeyValue.pair(new Windowed<>("1", new TimeWindow(1900, 2000)), "0+5"))));
@@ -419,7 +419,7 @@ public class SlidingWindowedKStreamImplTest {
                 final WindowStore<String, ValueAndTimestamp<Long>> windowStore =
                     driver.getTimestampedWindowStore("aggregated");
                 final List<KeyValue<Windowed<String>, ValueAndTimestamp<Long>>> data =
-                    StreamsTestUtils.toList(windowStore.fetch("1", "1", ofEpochMilli(0), ofEpochMilli(2000L)));
+                    StreamsTestUtils.toListAndCloseIterator(windowStore.fetch("1", "1", ofEpochMilli(0), ofEpochMilli(2000L)));
                 assertThat(data, equalTo(Arrays.asList(
                     KeyValue.pair(new Windowed<>("1", new TimeWindow(900, 1000)), ValueAndTimestamp.make("0+4", 1000L)),
                     KeyValue.pair(new Windowed<>("1", new TimeWindow(1900, 2000)), ValueAndTimestamp.make("0+5", 2000L)))));

streams/src/test/java/org/apache/kafka/streams/kstream/internals/TimeWindowedKStreamImplTest.java

@@ -239,7 +239,7 @@ public class TimeWindowedKStreamImplTest {
             {
                 final WindowStore<String, Long> windowStore = driver.getWindowStore("count-store");
                 final List<KeyValue<Windowed<String>, Long>> data =
-                    StreamsTestUtils.toList(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
+                    StreamsTestUtils.toListAndCloseIterator(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
 
                 if (withCache) {
                     // with cache returns all records (expired from underneath as well) as part of
@@ -266,7 +266,7 @@ public class TimeWindowedKStreamImplTest {
                 final WindowStore<String, ValueAndTimestamp<Long>> windowStore =
                     driver.getTimestampedWindowStore("count-store");
                 final List<KeyValue<Windowed<String>, ValueAndTimestamp<Long>>> data =
-                    StreamsTestUtils.toList(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
+                    StreamsTestUtils.toListAndCloseIterator(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
 
                 // the same values and logic described above applies here as well.
                 if (withCache) {
@@ -305,7 +305,7 @@ public class TimeWindowedKStreamImplTest {
             {
                 final WindowStore<String, String> windowStore = driver.getWindowStore("reduced");
                 final List<KeyValue<Windowed<String>, String>> data =
-                    StreamsTestUtils.toList(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
+                    StreamsTestUtils.toListAndCloseIterator(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
 
                 if (withCache) {
                     // with cache returns all records (expired from underneath as well) as part of
@@ -325,7 +325,7 @@ public class TimeWindowedKStreamImplTest {
             {
                 final WindowStore<String, ValueAndTimestamp<String>> windowStore = driver.getTimestampedWindowStore("reduced");
                 final List<KeyValue<Windowed<String>, ValueAndTimestamp<String>>> data =
-                    StreamsTestUtils.toList(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
+                    StreamsTestUtils.toListAndCloseIterator(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
 
                 // same logic/data as explained above.
                 if (withCache) {
@@ -358,7 +358,7 @@ public class TimeWindowedKStreamImplTest {
             {
                 final WindowStore<String, String> windowStore = driver.getWindowStore("aggregated");
                 final List<KeyValue<Windowed<String>, String>> data =
-                    StreamsTestUtils.toList(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
+                    StreamsTestUtils.toListAndCloseIterator(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
 
                 if (withCache) {
                     // with cache returns all records (expired from underneath as well) as part of
@@ -379,7 +379,7 @@ public class TimeWindowedKStreamImplTest {
             {
                 final WindowStore<String, ValueAndTimestamp<String>> windowStore = driver.getTimestampedWindowStore("aggregated");
                 final List<KeyValue<Windowed<String>, ValueAndTimestamp<String>>> data =
-                    StreamsTestUtils.toList(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
+                    StreamsTestUtils.toListAndCloseIterator(windowStore.fetch("1", "2", ofEpochMilli(0), ofEpochMilli(1000L)));
                 if (withCache) {
                     assertThat(data, equalTo(asList(
                             KeyValue.pair(new Windowed<>("1", new TimeWindow(0, 500)), ValueAndTimestamp.make("0+1+2", 15L)),

streams/src/test/java/org/apache/kafka/streams/state/internals/AbstractKeyValueStoreTest.java

@@ -38,11 +38,11 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
-import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 
+import static org.apache.kafka.test.StreamsTestUtils.toListAndCloseIterator;
 import static org.hamcrest.CoreMatchers.hasItem;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.core.IsEqual.equalTo;
@@ -53,18 +53,17 @@ import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.junit.jupiter.api.Assertions.fail;
 
-@SuppressWarnings("unchecked")
 public abstract class AbstractKeyValueStoreTest {
 
     protected abstract <K, V> KeyValueStore<K, V> createKeyValueStore(final StateStoreContext context);
-    protected InternalMockProcessorContext context;
+    protected InternalMockProcessorContext<?, ?> context;
     protected KeyValueStore<Integer, String> store;
     protected KeyValueStoreTestDriver<Integer, String> driver;
 
     @BeforeEach
     public void before() {
         driver = KeyValueStoreTestDriver.create(Integer.class, String.class);
-        context = (InternalMockProcessorContext) driver.context();
+        context = (InternalMockProcessorContext<?, ?>) driver.context();
         context.setTime(10);
         store = createKeyValueStore(context);
     }
@@ -75,16 +74,17 @@ public abstract class AbstractKeyValueStoreTest {
         driver.clear();
     }
 
-    private static Map<Integer, String> getContents(final KeyValueIterator<Integer, String> iter) {
+    private static Map<Integer, String> getContentsAndCloseIterator(final KeyValueIterator<Integer, String> iter) {
-        final HashMap<Integer, String> result = new HashMap<>();
+        try (iter) {
-        while (iter.hasNext()) {
+            final HashMap<Integer, String> result = new HashMap<>();
-            final KeyValue<Integer, String> entry = iter.next();
+            while (iter.hasNext()) {
-            result.put(entry.key, entry.value);
+                final KeyValue<Integer, String> entry = iter.next();
+                result.put(entry.key, entry.value);
+            }
+            return result;
         }
-        return result;
     }
 
-    @SuppressWarnings("unchecked")
     @Test
     public void shouldNotIncludeDeletedFromRangeResult() {
         store.close();
@@ -113,7 +113,7 @@ public abstract class AbstractKeyValueStoreTest {
 
         // should not include deleted records in iterator
         final Map<Integer, String> expectedContents = Collections.singletonMap(2, "two");
-        assertEquals(expectedContents, getContents(store.all()));
+        assertEquals(expectedContents, getContentsAndCloseIterator(store.all()));
     }
 
     @Test
@@ -142,7 +142,7 @@ public abstract class AbstractKeyValueStoreTest {
 
         // should not include deleted records in iterator
         final Map<Integer, String> expectedContents = Collections.singletonMap(2, "two");
-        assertEquals(expectedContents, getContents(store.all()));
+        assertEquals(expectedContents, getContentsAndCloseIterator(store.all()));
     }
 
     @Test
@@ -184,13 +184,13 @@ public abstract class AbstractKeyValueStoreTest {
         expectedContents.put(4, "four");
 
         // Check range iteration ...
-        assertEquals(expectedContents, getContents(store.range(2, 4)));
+        assertEquals(expectedContents, getContentsAndCloseIterator(store.range(2, 4)));
-        assertEquals(expectedContents, getContents(store.range(2, 6)));
+        assertEquals(expectedContents, getContentsAndCloseIterator(store.range(2, 6)));
 
         // Check all iteration ...
         expectedContents.put(0, "zero");
         expectedContents.put(1, "one");
-        assertEquals(expectedContents, getContents(store.all()));
+        assertEquals(expectedContents, getContentsAndCloseIterator(store.all()));
     }
 
     @Test
@@ -232,13 +232,13 @@ public abstract class AbstractKeyValueStoreTest {
         expectedContents.put(4, "four");
 
         // Check range iteration ...
-        assertEquals(expectedContents, getContents(store.reverseRange(2, 4)));
+        assertEquals(expectedContents, getContentsAndCloseIterator(store.reverseRange(2, 4)));
-        assertEquals(expectedContents, getContents(store.reverseRange(2, 6)));
+        assertEquals(expectedContents, getContentsAndCloseIterator(store.reverseRange(2, 6)));
 
         // Check all iteration ...
         expectedContents.put(0, "zero");
         expectedContents.put(1, "one");
-        assertEquals(expectedContents, getContents(store.reverseAll()));
+        assertEquals(expectedContents, getContentsAndCloseIterator(store.reverseAll()));
     }
 
     @Test
@@ -498,14 +498,10 @@ public abstract class AbstractKeyValueStoreTest {
 
         store.putAll(entries);
 
-        final List<KeyValue<Integer, String>> allReturned = new ArrayList<>();
+        final List<KeyValue<Integer, String>> allReturned = toListAndCloseIterator(store.all());
         final List<KeyValue<Integer, String>> expectedReturned =
             Arrays.asList(KeyValue.pair(1, "one"), KeyValue.pair(2, "two"));
-        final Iterator<KeyValue<Integer, String>> iterator = store.all();
 
-        while (iterator.hasNext()) {
-            allReturned.add(iterator.next());
-        }
         assertThat(allReturned, equalTo(expectedReturned));
     }
 
@@ -517,14 +513,10 @@ public abstract class AbstractKeyValueStoreTest {
 
         store.putAll(entries);
 
-        final List<KeyValue<Integer, String>> allReturned = new ArrayList<>();
+        final List<KeyValue<Integer, String>> allReturned = toListAndCloseIterator(store.reverseAll());
         final List<KeyValue<Integer, String>> expectedReturned =
             Arrays.asList(KeyValue.pair(2, "two"), KeyValue.pair(1, "one"));
-        final Iterator<KeyValue<Integer, String>> iterator = store.reverseAll();
 
-        while (iterator.hasNext()) {
-            allReturned.add(iterator.next());
-        }
         assertThat(allReturned, equalTo(expectedReturned));
     }
 
@@ -545,10 +537,10 @@ public abstract class AbstractKeyValueStoreTest {
 
         store.putAll(entries);
 
-        final Iterator<KeyValue<Integer, String>> iterator = store.range(2, 2);
+        try (final KeyValueIterator<Integer, String> iterator = store.range(2, 2)) {
-
+            assertEquals(iterator.next().value, store.get(2));
-        assertEquals(iterator.next().value, store.get(2));
+            assertFalse(iterator.hasNext());
-        assertFalse(iterator.hasNext());
+        }
     }
 
     @Test
@@ -560,10 +552,10 @@ public abstract class AbstractKeyValueStoreTest {
 
         store.putAll(entries);
 
-        final Iterator<KeyValue<Integer, String>> iterator = store.reverseRange(2, 2);
+        try (final KeyValueIterator<Integer, String> iterator = store.reverseRange(2, 2)) {
-
+            assertEquals(iterator.next().value, store.get(2));
-        assertEquals(iterator.next().value, store.get(2));
+            assertFalse(iterator.hasNext());
-        assertFalse(iterator.hasNext());
+        }
     }
 
     @Test

streams/src/test/java/org/apache/kafka/streams/state/internals/AbstractRocksDBSegmentedBytesStoreTest.java

@@ -25,6 +25,7 @@ import org.apache.kafka.common.header.internals.RecordHeaders;
 import org.apache.kafka.common.metrics.Metrics;
 import org.apache.kafka.common.record.RecordBatch;
 import org.apache.kafka.common.record.TimestampType;
+import org.apache.kafka.common.serialization.LongSerializer;
 import org.apache.kafka.common.serialization.Serdes;
 import org.apache.kafka.common.utils.Bytes;
 import org.apache.kafka.common.utils.LogContext;
@@ -36,7 +37,6 @@ import org.apache.kafka.streams.StreamsConfig.InternalConfig;
 import org.apache.kafka.streams.kstream.Window;
 import org.apache.kafka.streams.kstream.Windowed;
 import org.apache.kafka.streams.kstream.internals.SessionWindow;
-import org.apache.kafka.streams.processor.StateStoreContext;
 import org.apache.kafka.streams.processor.internals.ChangelogRecordDeserializationHelper;
 import org.apache.kafka.streams.processor.internals.MockStreamsMetrics;
 import org.apache.kafka.streams.processor.internals.ProcessorRecordContext;
@@ -88,7 +88,7 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment> {
 
     private final long windowSizeForTimeWindow = 500;
-    private InternalMockProcessorContext context;
+    private InternalMockProcessorContext<?, ?> context;
     private AbstractRocksDBSegmentedBytesStore<S> bytesStore;
     private File stateDir;
     private final Window[] windows = new Window[4];
@@ -140,7 +140,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
             new MockRecordCollector(),
             new ThreadCache(new LogContext("testCache "), 0, new MockStreamsMetrics(new Metrics()))
         );
-        bytesStore.init((StateStoreContext) context, bytesStore);
+        bytesStore.init(context, bytesStore);
     }
 
     @AfterEach
@@ -168,21 +168,21 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
             Bytes.wrap(keyA.getBytes()), 0, windows[2].start())) {
             // All Records expired as observed stream time = 60000 implying actual-from = 59001 (60000 - 1000 + 1)
             // for WindowKeySchema, to = 60000 while for SessionKeySchema, to = 30000
-            assertEquals(Collections.emptyList(), toList(values));
+            assertEquals(Collections.emptyList(), toListAndCloseIterator(values));
         }
 
         try (final KeyValueIterator<Bytes, byte[]> values = bytesStore.fetch(
             Bytes.wrap(keyA.getBytes()), Bytes.wrap(keyB.getBytes()), 0, windows[2].start())) {
             // All Records expired as observed stream time = 60000 implying actual-from = 59001 (60000 - 1000 + 1)
             // for WindowKeySchema, to = 60000 while for SessionKeySchema, to = 30000
-            assertEquals(Collections.emptyList(), toList(values));
+            assertEquals(Collections.emptyList(), toListAndCloseIterator(values));
         }
 
         try (final KeyValueIterator<Bytes, byte[]> values = bytesStore.fetch(
             null, Bytes.wrap(keyB.getBytes()), 0, windows[2].start())) {
             // All Records expired as observed stream time = 60000 implying actual-from = 59001 (60000 - 1000 + 1)
             // for WindowKeySchema, to = 60000 while for SessionKeySchema, to = 30000
-            assertEquals(Collections.emptyList(), toList(values));
+            assertEquals(Collections.emptyList(), toListAndCloseIterator(values));
         }
 
         try (final KeyValueIterator<Bytes, byte[]> values = bytesStore.fetch(
@@ -193,7 +193,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
                 KeyValue.pair(new Windowed<>(keyC, windows[3]), 200L)
             );
 
-            assertEquals(expected, toList(values));
+            assertEquals(expected, toListAndCloseIterator(values));
         }
 
         try (final KeyValueIterator<Bytes, byte[]> values = bytesStore.fetch(
@@ -204,7 +204,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
                 KeyValue.pair(new Windowed<>(keyC, windows[3]), 200L)
             );
 
-            assertEquals(expected, toList(values));
+            assertEquals(expected, toListAndCloseIterator(values));
         }
     }
 
@@ -225,7 +225,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
 
             // All Records expired as observed stream time = 60000 implying actual-from = 59001 (60000 - 1000 + 1)
             // for WindowKeySchema, to = 60000 while for SessionKeySchema, to = 30000
-            assertEquals(Collections.emptyList(), toList(values));
+            assertEquals(Collections.emptyList(), toListAndCloseIterator(values));
         }
 
         try (final KeyValueIterator<Bytes, byte[]> values = bytesStore.backwardFetch(
@@ -233,7 +233,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
 
             // All Records expired as observed stream time = 60000 implying actual-from = 59001 (60000 - 1000 + 1)
             // for WindowKeySchema, to = 60000 while for SessionKeySchema, to = 30000
-            assertEquals(Collections.emptyList(), toList(values));
+            assertEquals(Collections.emptyList(), toListAndCloseIterator(values));
         }
 
         try (final KeyValueIterator<Bytes, byte[]> values = bytesStore.backwardFetch(
@@ -241,7 +241,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
 
             // All Records expired as observed stream time = 60000 implying actual-from = 59001 (60000 - 1000 + 1)
             // for WindowKeySchema, to = 60000 while for SessionKeySchema, to = 30000
-            assertEquals(Collections.emptyList(), toList(values));
+            assertEquals(Collections.emptyList(), toListAndCloseIterator(values));
         }
 
         try (final KeyValueIterator<Bytes, byte[]> values = bytesStore.backwardFetch(
@@ -252,7 +252,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
                 KeyValue.pair(new Windowed<>(keyC, windows[3]), 200L)
             );
 
-            assertEquals(expected, toList(values));
+            assertEquals(expected, toListAndCloseIterator(values));
         }
 
         try (final KeyValueIterator<Bytes, byte[]> values = bytesStore.backwardFetch(
@@ -263,7 +263,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
                 KeyValue.pair(new Windowed<>(keyC, windows[3]), 200L)
             );
 
-            assertEquals(expected, toList(values));
+            assertEquals(expected, toListAndCloseIterator(values));
         }
     }
 
@@ -289,7 +289,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
                 expected.add(KeyValue.pair(new Windowed<>(key, windows[1]), 50L));
             }
 
-            assertEquals(expected, toList(results));
+            assertEquals(expected, toListAndCloseIterator(results));
         }
     }
 
@@ -322,7 +322,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
         bytesStore.put(serializeKey(new Windowed<>(key, windows[3])), serializeValue(1000));
         assertEquals(Set.of(segments.segmentName(0), segments.segmentName(1)), segmentDirs());
 
-        final List<KeyValue<Windowed<String>, Long>> results = toList(bytesStore.fetch(Bytes.wrap(key.getBytes()), 0, 1500));
+        final List<KeyValue<Windowed<String>, Long>> results = toListAndCloseIterator(bytesStore.fetch(Bytes.wrap(key.getBytes()), 0, 1500));
         /*
         * All records expired as observed stream time = 60,000 which sets actual-from to 59001(60,000 - 1000 + 1). to = 1500.
          */
@@ -355,7 +355,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
         /*
         * Only 1 record returned. observed stream time = 60000, actual from = 59001 (60000 - 1000 + 1) and to = Long.MAX.
          */
-        final List<KeyValue<Windowed<String>, Long>> results = toList(bytesStore.all());
+        final List<KeyValue<Windowed<String>, Long>> results = toListAndCloseIterator(bytesStore.all());
         assertEquals(
             Collections.singletonList(
                 KeyValue.pair(new Windowed<>(key, windows[3]), 100L)
@@ -388,7 +388,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
         /*
          * Only 1 record returned. observed stream time = 60000, actual from = 59001 (60000 - 1000 + 1) and to = 60,000.
          */
-        final List<KeyValue<Windowed<String>, Long>> results = toList(bytesStore.fetchAll(0L, 60_000L));
+        final List<KeyValue<Windowed<String>, Long>> results = toListAndCloseIterator(bytesStore.fetchAll(0L, 60_000L));
         assertEquals(
             Collections.singletonList(
                 KeyValue.pair(new Windowed<>(key, windows[3]), 100L)
@@ -422,8 +422,8 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
 
         bytesStore = getBytesStore();
 
-        bytesStore.init((StateStoreContext) context, bytesStore);
+        bytesStore.init(context, bytesStore);
-        final List<KeyValue<Windowed<String>, Long>> results = toList(bytesStore.fetch(Bytes.wrap(key.getBytes()), 0L, 60_000L));
+        final List<KeyValue<Windowed<String>, Long>> results = toListAndCloseIterator(bytesStore.fetch(Bytes.wrap(key.getBytes()), 0L, 60_000L));
         assertThat(
             results,
             equalTo(
@@ -456,8 +456,8 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
 
         bytesStore = getBytesStore();
 
-        bytesStore.init((StateStoreContext) context, bytesStore);
+        bytesStore.init(context, bytesStore);
-        final List<KeyValue<Windowed<String>, Long>> results = toList(bytesStore.fetch(Bytes.wrap(key.getBytes()), 0L, 60_000L));
+        final List<KeyValue<Windowed<String>, Long>> results = toListAndCloseIterator(bytesStore.fetch(Bytes.wrap(key.getBytes()), 0L, 60_000L));
         assertThat(
             results,
             equalTo(
@@ -479,7 +479,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
         // need to create a segment so we can attempt to write to it again.
         bytesStore.put(serializeKey(new Windowed<>(key, windows[0])), serializeValue(50));
         bytesStore.close();
-        bytesStore.init((StateStoreContext) context, bytesStore);
+        bytesStore.init(context, bytesStore);
         bytesStore.put(serializeKey(new Windowed<>(key, windows[1])), serializeValue(100));
     }
 
@@ -515,7 +515,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
     }
 
     private void shouldRestoreToByteStore() {
-        bytesStore.init((StateStoreContext) context, bytesStore);
+        bytesStore.init(context, bytesStore);
         // 0 segments initially.
         assertEquals(0, bytesStore.getSegments().size());
         final String key = "a";
@@ -533,7 +533,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
         final List<KeyValue<Windowed<String>, Long>> expected = new ArrayList<>();
         expected.add(new KeyValue<>(new Windowed<>(key, windows[3]), 100L));
 
-        final List<KeyValue<Windowed<String>, Long>> results = toList(bytesStore.all());
+        final List<KeyValue<Windowed<String>, Long>> results = toListAndCloseIterator(bytesStore.all());
         assertEquals(expected, results);
     }
 
@@ -541,7 +541,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
     @MethodSource("getKeySchemas")
     public void shouldMatchPositionAfterPut(final SegmentedBytesStore.KeySchema schema) {
         before(schema);
-        bytesStore.init((StateStoreContext) context, bytesStore);
+        bytesStore.init(context, bytesStore);
 
         final String keyA = "a";
         final String keyB = "b";
@@ -579,7 +579,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
                 Time.SYSTEM
         );
         bytesStore = getBytesStore();
-        bytesStore.init((StateStoreContext) context, bytesStore);
+        bytesStore.init(context, bytesStore);
         // 0 segments initially.
         assertEquals(0, bytesStore.getSegments().size());
 
@@ -594,7 +594,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
         final List<KeyValue<Windowed<String>, Long>> expected = new ArrayList<>();
         expected.add(new KeyValue<>(new Windowed<>(key, windows[3]), 200L));
 
-        final List<KeyValue<Windowed<String>, Long>> results = toList(bytesStore.all());
+        final List<KeyValue<Windowed<String>, Long>> results = toListAndCloseIterator(bytesStore.all());
         assertEquals(expected, results);
         assertThat(bytesStore.getPosition(), Matchers.notNullValue());
         assertThat(bytesStore.getPosition().getPartitionPositions(""), Matchers.notNullValue());
@@ -619,7 +619,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
                 Time.SYSTEM
         );
         bytesStore = getBytesStore();
-        bytesStore.init((StateStoreContext) context, bytesStore);
+        bytesStore.init(context, bytesStore);
         // 0 segments initially.
         assertEquals(0, bytesStore.getSegments().size());
 
@@ -634,7 +634,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
         final List<KeyValue<Windowed<String>, Long>> expected = new ArrayList<>();
         expected.add(new KeyValue<>(new Windowed<>(key, windows[3]), 200L));
 
-        final List<KeyValue<Windowed<String>, Long>> results = toList(bytesStore.all());
+        final List<KeyValue<Windowed<String>, Long>> results = toListAndCloseIterator(bytesStore.all());
         assertEquals(expected, results);
         assertThat(bytesStore.getPosition(), Matchers.notNullValue());
         assertThat(bytesStore.getPosition().getPartitionPositions("A"), Matchers.notNullValue());
@@ -661,7 +661,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
                 Time.SYSTEM
         );
         bytesStore = getBytesStore();
-        bytesStore.init((StateStoreContext) context, bytesStore);
+        bytesStore.init(context, bytesStore);
         // 0 segments initially.
         assertEquals(0, bytesStore.getSegments().size());
 
@@ -675,7 +675,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
          * SessionKeySchema, it's 1500. Which changes the actual-from while fetching. In case of SessionKeySchema, the
          * fetch happens from 501 to end while for WindowKeySchema it's from 1 to end.
          */
-        final List<KeyValue<Windowed<String>, Long>> results = toList(bytesStore.all());
+        final List<KeyValue<Windowed<String>, Long>> results = toListAndCloseIterator(bytesStore.all());
         if (schema instanceof SessionKeySchema) {
             assertEquals(Collections.emptyList(), results);
         } else {
@@ -705,7 +705,7 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
                 Time.SYSTEM
         );
         bytesStore = getBytesStore();
-        bytesStore.init((StateStoreContext) context, bytesStore);
+        bytesStore.init(context, bytesStore);
         bytesStore.restoreAllInternal(getChangelogRecordsWithoutHeaders());
         assertThat(bytesStore.getPosition(), is(Position.emptyPosition()));
     }
@@ -816,13 +816,13 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
         before(schema);
         final Properties streamsConfig = StreamsTestUtils.getStreamsConfig();
         final AbstractRocksDBSegmentedBytesStore<S> bytesStore = getBytesStore();
-        final InternalMockProcessorContext context = new InternalMockProcessorContext(
+        final InternalMockProcessorContext<?, ?> context = new InternalMockProcessorContext<>(
             TestUtils.tempDirectory(),
             new StreamsConfig(streamsConfig)
         );
         final Time time = Time.SYSTEM;
         context.setSystemTimeMs(time.milliseconds());
-        bytesStore.init((StateStoreContext) context, bytesStore);
+        bytesStore.init(context, bytesStore);
 
         // write a record to advance stream time, with a high enough timestamp
         // that the subsequent record in windows[0] will already be expired.
@@ -878,36 +878,40 @@ public abstract class AbstractRocksDBSegmentedBytesStoreTest<S extends Segment>
         }
     }
 
+    @SuppressWarnings("resource")
     private byte[] serializeValue(final long value) {
-        return Serdes.Long().serializer().serialize("", value);
+        return new LongSerializer().serialize("", value);
     }
 
-    private List<KeyValue<Windowed<String>, Long>> toList(final KeyValueIterator<Bytes, byte[]> iterator) {
+    @SuppressWarnings("resource")
-        final List<KeyValue<Windowed<String>, Long>> results = new ArrayList<>();
+    private List<KeyValue<Windowed<String>, Long>> toListAndCloseIterator(final KeyValueIterator<Bytes, byte[]> iterator) {
-        final StateSerdes<String, Long> stateSerdes = StateSerdes.withBuiltinTypes("dummy", String.class, Long.class);
+        try (iterator) {
-        while (iterator.hasNext()) {
+            final List<KeyValue<Windowed<String>, Long>> results = new ArrayList<>();
-            final KeyValue<Bytes, byte[]> next = iterator.next();
+            final StateSerdes<String, Long> stateSerdes = StateSerdes.withBuiltinTypes("dummy", String.class, Long.class);
-            if (schema instanceof WindowKeySchema) {
+            while (iterator.hasNext()) {
-                final KeyValue<Windowed<String>, Long> deserialized = KeyValue.pair(
+                final KeyValue<Bytes, byte[]> next = iterator.next();
-                    WindowKeySchema.fromStoreKey(
+                if (schema instanceof WindowKeySchema) {
-                        next.key.get(),
+                    final KeyValue<Windowed<String>, Long> deserialized = KeyValue.pair(
-                        windowSizeForTimeWindow,
+                        WindowKeySchema.fromStoreKey(
-                        stateSerdes.keyDeserializer(),
+                            next.key.get(),
-                        stateSerdes.topic()
+                            windowSizeForTimeWindow,
-                    ),
+                            stateSerdes.keyDeserializer(),
-                    stateSerdes.valueDeserializer().deserialize("dummy", next.value)
+                            stateSerdes.topic()
-                );
+                        ),
-                results.add(deserialized);
+                        stateSerdes.valueDeserializer().deserialize("dummy", next.value)
-            } else if (schema instanceof SessionKeySchema) {
+                    );
-                final KeyValue<Windowed<String>, Long> deserialized = KeyValue.pair(
+                    results.add(deserialized);
-                    SessionKeySchema.from(next.key.get(), stateSerdes.keyDeserializer(), "dummy"),
+                } else if (schema instanceof SessionKeySchema) {
-                    stateSerdes.valueDeserializer().deserialize("dummy", next.value)
+                    final KeyValue<Windowed<String>, Long> deserialized = KeyValue.pair(
-                );
+                        SessionKeySchema.from(next.key.get(), stateSerdes.keyDeserializer(), "dummy"),
-                results.add(deserialized);
+                        stateSerdes.valueDeserializer().deserialize("dummy", next.value)
-            } else {
+                    );
-                throw new IllegalStateException("Unrecognized serde schema");
+                    results.add(deserialized);
+                } else {
+                    throw new IllegalStateException("Unrecognized serde schema");
+                }
             }
+            return results;
         }
-        return results;
     }
 }

streams/src/test/java/org/apache/kafka/streams/state/internals/AbstractRocksDBWindowStoreTest.java

@@ -23,7 +23,6 @@ import org.apache.kafka.common.serialization.Serdes;
 import org.apache.kafka.common.utils.Bytes;
 import org.apache.kafka.common.utils.Utils;
 import org.apache.kafka.streams.KeyValue;
-import org.apache.kafka.streams.processor.StateStoreContext;
 import org.apache.kafka.streams.processor.internals.ProcessorRecordContext;
 import org.apache.kafka.streams.query.Position;
 import org.apache.kafka.streams.state.Stores;
@@ -45,7 +44,7 @@ import static java.util.Arrays.asList;
 import static java.util.Objects.requireNonNull;
 import static org.apache.kafka.common.utils.Utils.mkEntry;
 import static org.apache.kafka.common.utils.Utils.mkMap;
-import static org.apache.kafka.test.StreamsTestUtils.valuesToSet;
+import static org.apache.kafka.test.StreamsTestUtils.valuesToSetAndCloseIterator;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 
@@ -177,7 +176,7 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
         // expired record
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         0,
                         ofEpochMilli(startTime - WINDOW_SIZE),
                         ofEpochMilli(startTime + WINDOW_SIZE))));
@@ -193,7 +192,7 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
         if (storeType() == StoreType.RocksDBWindowStore) {
             assertEquals(
                     new HashSet<>(Collections.emptyList()),
-                    valuesToSet(windowStore.fetch(
+                    valuesToSetAndCloseIterator(windowStore.fetch(
                             1,
                             ofEpochMilli(startTime + increment - WINDOW_SIZE),
                             ofEpochMilli(startTime + increment + WINDOW_SIZE))));
@@ -201,32 +200,32 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
         } else {
             assertEquals(
                     new HashSet<>(Collections.singletonList("one")),
-                    valuesToSet(windowStore.fetch(
+                    valuesToSetAndCloseIterator(windowStore.fetch(
                             1,
                             ofEpochMilli(startTime + increment - WINDOW_SIZE),
                             ofEpochMilli(startTime + increment + WINDOW_SIZE))));
         }
         assertEquals(
                 new HashSet<>(Collections.singletonList("two")),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         2,
                         ofEpochMilli(startTime + increment * 2 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 2 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         3,
                         ofEpochMilli(startTime + increment * 3 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 3 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.singletonList("four")),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         4,
                         ofEpochMilli(startTime + increment * 4 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 4 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.singletonList("five")),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         5,
                         ofEpochMilli(startTime + increment * 5 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 5 + WINDOW_SIZE))));
@@ -243,13 +242,13 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
 
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         0,
                         ofEpochMilli(startTime - WINDOW_SIZE),
                         ofEpochMilli(startTime + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         1,
                         ofEpochMilli(startTime + increment - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment + WINDOW_SIZE))));
@@ -266,7 +265,7 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
             assertEquals(
                     // expired record
                     new HashSet<>(Collections.emptyList()),
-                    valuesToSet(windowStore.fetch(
+                    valuesToSetAndCloseIterator(windowStore.fetch(
                             2,
                             ofEpochMilli(startTime + increment * 2 - WINDOW_SIZE),
                             ofEpochMilli(startTime + increment * 2 + WINDOW_SIZE))));
@@ -274,32 +273,32 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
             assertEquals(
                     // expired record
                     new HashSet<>(Collections.singletonList("two")),
-                    valuesToSet(windowStore.fetch(
+                    valuesToSetAndCloseIterator(windowStore.fetch(
                             2,
                             ofEpochMilli(startTime + increment * 2 - WINDOW_SIZE),
                             ofEpochMilli(startTime + increment * 2 + WINDOW_SIZE))));
         }
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         3,
                         ofEpochMilli(startTime + increment * 3 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 3 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.singletonList("four")),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         4,
                         ofEpochMilli(startTime + increment * 4 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 4 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.singletonList("five")),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         5,
                         ofEpochMilli(startTime + increment * 5 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 5 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.singletonList("six")),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         6,
                         ofEpochMilli(startTime + increment * 6 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 6 + WINDOW_SIZE))));
@@ -316,50 +315,50 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
 
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         0,
                         ofEpochMilli(startTime - WINDOW_SIZE),
                         ofEpochMilli(startTime + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         1,
                         ofEpochMilli(startTime + increment - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment + WINDOW_SIZE))));
         assertEquals(
                 // expired record
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         2,
                         ofEpochMilli(startTime + increment * 2 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 2 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         3,
                         ofEpochMilli(startTime + increment * 3 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 3 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.singletonList("four")),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         4,
                         ofEpochMilli(startTime + increment * 4 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 4 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.singletonList("five")),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         5,
                         ofEpochMilli(startTime + increment * 5 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 5 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.singletonList("six")),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         6,
                         ofEpochMilli(startTime + increment * 6 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 6 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.singletonList("seven")),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         7,
                         ofEpochMilli(startTime + increment * 7 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 7 + WINDOW_SIZE))));
@@ -376,25 +375,25 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
 
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         0,
                         ofEpochMilli(startTime - WINDOW_SIZE),
                         ofEpochMilli(startTime + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         1,
                         ofEpochMilli(startTime + increment - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         2,
                         ofEpochMilli(startTime + increment * 2 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 2 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         3,
                         ofEpochMilli(startTime + increment * 3 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 3 + WINDOW_SIZE))));
@@ -402,7 +401,7 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
             assertEquals(
                     // expired record
                     new HashSet<>(Collections.emptyList()),
-                    valuesToSet(windowStore.fetch(
+                    valuesToSetAndCloseIterator(windowStore.fetch(
                             4,
                             ofEpochMilli(startTime + increment * 4 - WINDOW_SIZE),
                             ofEpochMilli(startTime + increment * 4 + WINDOW_SIZE))));
@@ -410,7 +409,7 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
             assertEquals(
                     // expired record
                     new HashSet<>(Collections.singletonList("four")),
-                    valuesToSet(windowStore.fetch(
+                    valuesToSetAndCloseIterator(windowStore.fetch(
                             4,
                             ofEpochMilli(startTime + increment * 4 - WINDOW_SIZE),
                             ofEpochMilli(startTime + increment * 4 + WINDOW_SIZE))));
@@ -418,25 +417,25 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
         }
         assertEquals(
                 new HashSet<>(Collections.singletonList("five")),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         5,
                         ofEpochMilli(startTime + increment * 5 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 5 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.singletonList("six")),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         6,
                         ofEpochMilli(startTime + increment * 6 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 6 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.singletonList("seven")),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         7,
                         ofEpochMilli(startTime + increment * 7 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 7 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.singletonList("eight")),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         8,
                         ofEpochMilli(startTime + increment * 8 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 8 + WINDOW_SIZE))));
@@ -458,7 +457,7 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
         windowStore.close();
         windowStore = buildWindowStore(RETENTION_PERIOD, WINDOW_SIZE, true, Serdes.Integer(),
                 Serdes.String());
-        windowStore.init((StateStoreContext) context, windowStore);
+        windowStore.init(context, windowStore);
 
         context.setTime(0L);
         windowStore.put(0, "v", 0);
@@ -480,14 +479,14 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
                 segmentDirs(baseDir)
         );
 
-        WindowStoreIterator iter;
         int fetchedCount;
 
-        iter = windowStore.fetch(0, ofEpochMilli(0L), ofEpochMilli(SEGMENT_INTERVAL * 4));
+        try (final WindowStoreIterator<String> iter = windowStore.fetch(0, ofEpochMilli(0L), ofEpochMilli(SEGMENT_INTERVAL * 4))) {
-        fetchedCount = 0;
+            fetchedCount = 0;
-        while (iter.hasNext()) {
+            while (iter.hasNext()) {
-            iter.next();
+                iter.next();
-            fetchedCount++;
+                fetchedCount++;
+            }
         }
         assertEquals(4, fetchedCount);
 
@@ -498,11 +497,12 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
 
         windowStore.put(0, "v", SEGMENT_INTERVAL * 3);
 
-        iter = windowStore.fetch(0, ofEpochMilli(0L), ofEpochMilli(SEGMENT_INTERVAL * 4));
+        try (final WindowStoreIterator<String> iter = windowStore.fetch(0, ofEpochMilli(0L), ofEpochMilli(SEGMENT_INTERVAL * 4))) {
-        fetchedCount = 0;
+            fetchedCount = 0;
-        while (iter.hasNext()) {
+            while (iter.hasNext()) {
-            iter.next();
+                iter.next();
-            fetchedCount++;
+                fetchedCount++;
+            }
         }
         // 1 extra record is expired in the case of RocksDBWindowStore as
         // actualFrom = observedStreamTime - retentionPeriod + 1. The +1
@@ -520,11 +520,12 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
 
         windowStore.put(0, "v", SEGMENT_INTERVAL * 5);
 
-        iter = windowStore.fetch(0, ofEpochMilli(SEGMENT_INTERVAL * 4), ofEpochMilli(SEGMENT_INTERVAL * 10));
+        try (final WindowStoreIterator<String> iter = windowStore.fetch(0, ofEpochMilli(SEGMENT_INTERVAL * 4), ofEpochMilli(SEGMENT_INTERVAL * 10))) {
-        fetchedCount = 0;
+            fetchedCount = 0;
-        while (iter.hasNext()) {
+            while (iter.hasNext()) {
-            iter.next();
+                iter.next();
-            fetchedCount++;
+                fetchedCount++;
+            }
         }
 
         // the latest record has a timestamp > 60k. So, the +1 in actualFrom calculation in
@@ -552,7 +553,7 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
         windowStore.close();
 
         windowStore = buildWindowStore(RETENTION_PERIOD, WINDOW_SIZE, false, Serdes.Integer(), Serdes.String());
-        windowStore.init((StateStoreContext) context, windowStore);
+        windowStore.init(context, windowStore);
 
         // put something in the store to advance its stream time and expire the old segments
         windowStore.put(1, "v", 6L * SEGMENT_INTERVAL);
@@ -568,7 +569,7 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
 
         assertEquals(expected, actual);
 
-        try (final WindowStoreIterator iter = windowStore.fetch(0, ofEpochMilli(0L), ofEpochMilli(1000000L))) {
+        try (final WindowStoreIterator<String> iter = windowStore.fetch(0, ofEpochMilli(0L), ofEpochMilli(1000000L))) {
             while (iter.hasNext()) {
                 iter.next();
             }
@@ -583,7 +584,6 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
         );
     }
 
-    @SuppressWarnings("unchecked")
     @Test
     public void testRestore() throws Exception {
         final long startTime = SEGMENT_INTERVAL * 2;
@@ -610,62 +610,62 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
                 false,
                 Serdes.Integer(),
                 Serdes.String());
-        windowStore.init((StateStoreContext) context, windowStore);
+        windowStore.init(context, windowStore);
 
         // For all tests, for WindowStore actualFrom is computed using observedStreamTime - retention + 1.
         // while for TimeOrderedWindowStores, actualFrom = observedStreamTime - retention
 
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         0,
                         ofEpochMilli(startTime - WINDOW_SIZE),
                         ofEpochMilli(startTime + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         1,
                         ofEpochMilli(startTime + increment - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         2,
                         ofEpochMilli(startTime + increment * 2 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 2 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         3,
                         ofEpochMilli(startTime + increment * 3 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 3 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         4,
                         ofEpochMilli(startTime + increment * 4 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 4 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         5,
                         ofEpochMilli(startTime + increment * 5 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 5 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         6,
                         ofEpochMilli(startTime + increment * 6 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 6 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         7,
                         ofEpochMilli(startTime + increment * 7 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 7 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         8,
                         ofEpochMilli(startTime + increment * 8 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 8 + WINDOW_SIZE))));
@@ -679,25 +679,25 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
 
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         0,
                         ofEpochMilli(startTime - WINDOW_SIZE),
                         ofEpochMilli(startTime + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         1,
                         ofEpochMilli(startTime + increment - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         2,
                         ofEpochMilli(startTime + increment * 2 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 2 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.emptyList()),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         3,
                         ofEpochMilli(startTime + increment * 3 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 3 + WINDOW_SIZE))));
@@ -713,14 +713,14 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
         if (storeType() == StoreType.RocksDBWindowStore) {
             assertEquals(
                     new HashSet<>(Collections.emptyList()),
-                    valuesToSet(windowStore.fetch(
+                    valuesToSetAndCloseIterator(windowStore.fetch(
                             4,
                             ofEpochMilli(startTime + increment * 4 - WINDOW_SIZE),
                             ofEpochMilli(startTime + increment * 4 + WINDOW_SIZE))));
         } else {
             assertEquals(
                     new HashSet<>(Collections.singletonList("four")),
-                    valuesToSet(windowStore.fetch(
+                    valuesToSetAndCloseIterator(windowStore.fetch(
                             4,
                             ofEpochMilli(startTime + increment * 4 - WINDOW_SIZE),
                             ofEpochMilli(startTime + increment * 4 + WINDOW_SIZE))));
@@ -728,25 +728,25 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
         }
         assertEquals(
                 new HashSet<>(Collections.singletonList("five")),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         5,
                         ofEpochMilli(startTime + increment * 5 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 5 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.singletonList("six")),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         6,
                         ofEpochMilli(startTime + increment * 6 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 6 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.singletonList("seven")),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         7,
                         ofEpochMilli(startTime + increment * 7 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 7 + WINDOW_SIZE))));
         assertEquals(
                 new HashSet<>(Collections.singletonList("eight")),
-                valuesToSet(windowStore.fetch(
+                valuesToSetAndCloseIterator(windowStore.fetch(
                         8,
                         ofEpochMilli(startTime + increment * 8 - WINDOW_SIZE),
                         ofEpochMilli(startTime + increment * 8 + WINDOW_SIZE))));
@@ -762,11 +762,12 @@ public abstract class AbstractRocksDBWindowStoreTest extends AbstractWindowBytes
         );
     }
 
+    @SuppressWarnings({"rawtypes", "unchecked"})
     @Test
     public void shouldMatchPositionAfterPut() {
         final MeteredWindowStore<Integer, String> meteredSessionStore = (MeteredWindowStore<Integer, String>) windowStore;
         final ChangeLoggingWindowBytesStore changeLoggingSessionBytesStore = (ChangeLoggingWindowBytesStore) meteredSessionStore.wrapped();
-        final WrappedStateStore rocksDBWindowStore = (WrappedStateStore) changeLoggingSessionBytesStore.wrapped();
+        final WrappedStateStore<WrappedStateStore, Integer, String> rocksDBWindowStore = (WrappedStateStore<WrappedStateStore, Integer, String>) changeLoggingSessionBytesStore.wrapped();
 
         context.setRecordContext(new ProcessorRecordContext(0, 1, 0, "", new RecordHeaders()));
         windowStore.put(0, "0", SEGMENT_INTERVAL);

streams/src/test/java/org/apache/kafka/streams/state/internals/AbstractSessionBytesStoreTest.java

@@ -21,8 +21,10 @@ import org.apache.kafka.common.Metric;
 import org.apache.kafka.common.MetricName;
 import org.apache.kafka.common.header.internals.RecordHeaders;
 import org.apache.kafka.common.metrics.Metrics;
+import org.apache.kafka.common.serialization.IntegerSerializer;
 import org.apache.kafka.common.serialization.Serde;
 import org.apache.kafka.common.serialization.Serdes;
+import org.apache.kafka.common.serialization.StringDeserializer;
 import org.apache.kafka.common.utils.Bytes;
 import org.apache.kafka.common.utils.LogCaptureAppender;
 import org.apache.kafka.common.utils.LogContext;
@@ -31,7 +33,6 @@ import org.apache.kafka.streams.KeyValue;
 import org.apache.kafka.streams.StreamsConfig;
 import org.apache.kafka.streams.kstream.Windowed;
 import org.apache.kafka.streams.kstream.internals.SessionWindow;
-import org.apache.kafka.streams.processor.StateStoreContext;
 import org.apache.kafka.streams.processor.internals.MockStreamsMetrics;
 import org.apache.kafka.streams.processor.internals.ProcessorRecordContext;
 import org.apache.kafka.streams.query.Position;
@@ -93,7 +94,7 @@ public abstract class AbstractSessionBytesStoreTest {
 
     private MockRecordCollector recordCollector;
 
-    InternalMockProcessorContext context;
+    InternalMockProcessorContext<?, ?> context;
 
     <K, V> SessionStore<K, V> buildSessionStore(final long retentionPeriod,
                                                          final Serde<K> keySerde,
@@ -159,7 +160,7 @@ public abstract class AbstractSessionBytesStoreTest {
                 new MockStreamsMetrics(new Metrics())));
         context.setTime(1L);
 
-        sessionStore.init((StateStoreContext) context, sessionStore);
+        sessionStore.init(context, sessionStore);
     }
 
     @AfterEach
@@ -240,6 +241,7 @@ public abstract class AbstractSessionBytesStoreTest {
         }
     }
 
+    @SuppressWarnings("resource")
     @Test
     public void shouldFindSessionsForTimeRange() {
         sessionStore.put(new Windowed<>("a", new SessionWindow(0, 0)), 5L);
@@ -552,7 +554,7 @@ public abstract class AbstractSessionBytesStoreTest {
     public void shouldFetchExactKeys() {
         sessionStore.close();
         sessionStore = buildSessionStore(0x7a00000000000000L, Serdes.String(), Serdes.Long());
-        sessionStore.init((StateStoreContext) context, sessionStore);
+        sessionStore.init(context, sessionStore);
 
         sessionStore.put(new Windowed<>("a", new SessionWindow(0, 0)), 1L);
         sessionStore.put(new Windowed<>("aa", new SessionWindow(0, 10)), 2L);
@@ -608,7 +610,7 @@ public abstract class AbstractSessionBytesStoreTest {
     public void shouldBackwardFetchExactKeys() {
         sessionStore.close();
         sessionStore = buildSessionStore(0x7a00000000000000L, Serdes.String(), Serdes.Long());
-        sessionStore.init((StateStoreContext) context, sessionStore);
+        sessionStore.init(context, sessionStore);
 
         sessionStore.put(new Windowed<>("a", new SessionWindow(0, 0)), 1L);
         sessionStore.put(new Windowed<>("aa", new SessionWindow(0, 10)), 2L);
@@ -665,7 +667,7 @@ public abstract class AbstractSessionBytesStoreTest {
         final SessionStore<Bytes, String> sessionStore =
             buildSessionStore(RETENTION_PERIOD, Serdes.Bytes(), Serdes.String());
 
-        sessionStore.init((StateStoreContext) context, sessionStore);
+        sessionStore.init(context, sessionStore);
 
         final Bytes key1 = Bytes.wrap(new byte[] {0});
         final Bytes key2 = Bytes.wrap(new byte[] {0, 0});
@@ -704,7 +706,7 @@ public abstract class AbstractSessionBytesStoreTest {
         final SessionStore<Bytes, String> sessionStore =
             buildSessionStore(RETENTION_PERIOD, Serdes.Bytes(), Serdes.String());
 
-        sessionStore.init((StateStoreContext) context, sessionStore);
+        sessionStore.init(context, sessionStore);
 
         final Bytes key1 = Bytes.wrap(new byte[] {0});
         final Bytes key2 = Bytes.wrap(new byte[] {0, 0});
@@ -747,10 +749,11 @@ public abstract class AbstractSessionBytesStoreTest {
         sessionStore.put(new Windowed<>("aa", new SessionWindow(10, 20)), 4L);
 
         try (final KeyValueIterator<Windowed<String>, Long> iterator = sessionStore.findSessions("a", 0L, 20)) {
-
+            assertEquals(new Windowed<>("a", new SessionWindow(0L, 0L)), iterator.peekNextKey());
-            assertEquals(iterator.peekNextKey(), new Windowed<>("a", new SessionWindow(0L, 0L)));
+            final Windowed<String> k1 = iterator.peekNextKey();
-            assertEquals(iterator.peekNextKey(), iterator.next().key);
+            assertEquals(iterator.next().key, k1);
-            assertEquals(iterator.peekNextKey(), iterator.next().key);
+            final Windowed<String> k2 = iterator.peekNextKey();
+            assertEquals(iterator.next().key, k2);
             assertFalse(iterator.hasNext());
         }
     }
@@ -763,15 +766,15 @@ public abstract class AbstractSessionBytesStoreTest {
         sessionStore.put(new Windowed<>("aa", new SessionWindow(10, 20)), 4L);
 
         try (final KeyValueIterator<Windowed<String>, Long> iterator = sessionStore.backwardFindSessions("a", 0L, 20)) {
-
+            assertEquals(new Windowed<>("a", new SessionWindow(10L, 20L)), iterator.peekNextKey());
-            assertEquals(iterator.peekNextKey(), new Windowed<>("a", new SessionWindow(10L, 20L)));
+            final Windowed<String> k1 = iterator.peekNextKey();
-            assertEquals(iterator.peekNextKey(), iterator.next().key);
+            assertEquals(iterator.next().key, k1);
-            assertEquals(iterator.peekNextKey(), iterator.next().key);
+            final Windowed<String> k2 = iterator.peekNextKey();
+            assertEquals(iterator.next().key, k2);
             assertFalse(iterator.hasNext());
         }
     }
 
-    @SuppressWarnings("unchecked")
     @Test
     public void shouldRestore() {
         final List<KeyValue<Windowed<String>, Long>> expected = Arrays.asList(
@@ -842,7 +845,7 @@ public abstract class AbstractSessionBytesStoreTest {
     public void shouldMeasureExpiredRecords() {
         final Properties streamsConfig = StreamsTestUtils.getStreamsConfig();
         final SessionStore<String, Long> sessionStore = buildSessionStore(RETENTION_PERIOD, Serdes.String(), Serdes.Long());
-        final InternalMockProcessorContext context = new InternalMockProcessorContext(
+        final InternalMockProcessorContext<?, ?> context = new InternalMockProcessorContext<>(
             TestUtils.tempDirectory(),
             new StreamsConfig(streamsConfig),
             recordCollector
@@ -850,7 +853,7 @@ public abstract class AbstractSessionBytesStoreTest {
         final Time time = Time.SYSTEM;
         context.setTime(1L);
         context.setSystemTimeMs(time.milliseconds());
-        sessionStore.init((StateStoreContext) context, sessionStore);
+        sessionStore.init(context, sessionStore);
 
         // Advance stream time by inserting record with large enough timestamp that records with timestamp 0 are expired
         // Note that rocksdb will only expire segments at a time (where segment interval = 60,000 for this retention period)
@@ -894,11 +897,13 @@ public abstract class AbstractSessionBytesStoreTest {
         sessionStore.remove(new Windowed<>("a", new SessionWindow(0, 1)));
     }
 
+    @SuppressWarnings("resource")
     @Test
     public void shouldThrowNullPointerExceptionOnFindSessionsNullKey() {
         assertThrows(NullPointerException.class, () -> sessionStore.findSessions(null, 1L, 2L));
     }
 
+    @SuppressWarnings("resource")
     @Test
     public void shouldThrowNullPointerExceptionOnFetchNullKey() {
         assertThrows(NullPointerException.class, () -> sessionStore.fetch(null));
@@ -914,12 +919,11 @@ public abstract class AbstractSessionBytesStoreTest {
         assertThrows(NullPointerException.class, () -> sessionStore.put(null, 1L));
     }
 
+    @SuppressWarnings("resource")
     @Test
     public void shouldNotThrowInvalidRangeExceptionWithNegativeFromKey() {
-        final String keyFrom = Serdes.String().deserializer()
+        final String keyFrom = new StringDeserializer().deserialize("", new IntegerSerializer().serialize("", -1));
-            .deserialize("", Serdes.Integer().serializer().serialize("", -1));
+        final String keyTo = new StringDeserializer().deserialize("", new IntegerSerializer().serialize("", 1));
-        final String keyTo = Serdes.String().deserializer()
-            .deserialize("", Serdes.Integer().serializer().serialize("", 1));
 
         try (final LogCaptureAppender appender = LogCaptureAppender.createAndRegister();
              final KeyValueIterator<Windowed<String>, Long> iterator = sessionStore.findSessions(keyFrom, keyTo, 0L, 10L)) {
@@ -968,16 +972,12 @@ public abstract class AbstractSessionBytesStoreTest {
 
     @Test
     public void shouldMatchPositionAfterPut() {
-        final MeteredSessionStore<String, Long> meteredSessionStore = (MeteredSessionStore<String, Long>) sessionStore;
-        final ChangeLoggingSessionBytesStore changeLoggingSessionBytesStore = (ChangeLoggingSessionBytesStore) meteredSessionStore.wrapped();
-        final SessionStore wrapped = (SessionStore) changeLoggingSessionBytesStore.wrapped();
-
         context.setRecordContext(new ProcessorRecordContext(0, 1, 0, "", new RecordHeaders()));
-        sessionStore.put(new Windowed<String>("a", new SessionWindow(0, 0)), 1L);
+        sessionStore.put(new Windowed<>("a", new SessionWindow(0, 0)), 1L);
         context.setRecordContext(new ProcessorRecordContext(0, 2, 0, "", new RecordHeaders()));
-        sessionStore.put(new Windowed<String>("aa", new SessionWindow(0, 10)), 2L);
+        sessionStore.put(new Windowed<>("aa", new SessionWindow(0, 10)), 2L);
         context.setRecordContext(new ProcessorRecordContext(0, 3, 0, "", new RecordHeaders()));
-        sessionStore.put(new Windowed<String>("a", new SessionWindow(10, 20)), 3L);
+        sessionStore.put(new Windowed<>("a", new SessionWindow(10, 20)), 3L);
 
         final Position expected = Position.fromMap(mkMap(mkEntry("", mkMap(mkEntry(0, 3L)))));
         final Position actual = sessionStore.getPosition();

streams/src/test/java/org/apache/kafka/streams/state/internals/AbstractWindowBytesStoreTest.java

@@ -30,7 +30,6 @@ import org.apache.kafka.common.utils.Time;
 import org.apache.kafka.streams.KeyValue;
 import org.apache.kafka.streams.StreamsConfig;
 import org.apache.kafka.streams.kstream.Windowed;
-import org.apache.kafka.streams.processor.StateStoreContext;
 import org.apache.kafka.streams.processor.internals.MockStreamsMetrics;
 import org.apache.kafka.streams.processor.internals.ProcessorRecordContext;
 import org.apache.kafka.streams.state.KeyValueIterator;
@@ -60,9 +59,9 @@ import static java.time.Instant.ofEpochMilli;
 import static java.util.Arrays.asList;
 import static org.apache.kafka.common.utils.Utils.mkEntry;
 import static org.apache.kafka.common.utils.Utils.mkMap;
-import static org.apache.kafka.test.StreamsTestUtils.toList;
+import static org.apache.kafka.test.StreamsTestUtils.toListAndCloseIterator;
 import static org.apache.kafka.test.StreamsTestUtils.toSet;
-import static org.apache.kafka.test.StreamsTestUtils.valuesToSet;
+import static org.apache.kafka.test.StreamsTestUtils.valuesToSetAndCloseIterator;
 import static org.hamcrest.CoreMatchers.equalTo;
 import static org.hamcrest.CoreMatchers.hasItem;
 import static org.hamcrest.MatcherAssert.assertThat;
@@ -89,7 +88,7 @@ public abstract class AbstractWindowBytesStoreTest {
     final KeyValue<Windowed<Integer>, String> five = windowedPair(5, "five", defaultStartTime + 5);
 
     WindowStore<Integer, String> windowStore;
-    InternalMockProcessorContext context;
+    InternalMockProcessorContext<?, ?> context;
     MockRecordCollector recordCollector;
 
     final File baseDir = TestUtils.tempDirectory("test");
@@ -117,7 +116,7 @@ public abstract class AbstractWindowBytesStoreTest {
                 new MockStreamsMetrics(new Metrics())));
         context.setTime(1L);
 
-        windowStore.init((StateStoreContext) context, windowStore);
+        windowStore.init(context, windowStore);
     }
 
     @AfterEach
@@ -131,12 +130,12 @@ public abstract class AbstractWindowBytesStoreTest {
 
         assertEquals(
             new HashSet<>(Collections.singletonList("zero")),
-            valuesToSet(windowStore.fetch(
+            valuesToSetAndCloseIterator(windowStore.fetch(
                 0,
-                ofEpochMilli(defaultStartTime + 0 - WINDOW_SIZE),
+                ofEpochMilli(defaultStartTime - WINDOW_SIZE),
-                ofEpochMilli(defaultStartTime + 0 + WINDOW_SIZE))));
+                ofEpochMilli(defaultStartTime + WINDOW_SIZE))));
 
-        putSecondBatch(windowStore, defaultStartTime, context);
+        putSecondBatch(windowStore, defaultStartTime);
 
         assertEquals("two+1", windowStore.fetch(2, defaultStartTime + 3L));
         assertEquals("two+2", windowStore.fetch(2, defaultStartTime + 4L));
@@ -147,91 +146,91 @@ public abstract class AbstractWindowBytesStoreTest {
 
         assertEquals(
             new HashSet<>(Collections.emptyList()),
-            valuesToSet(windowStore.fetch(
+            valuesToSetAndCloseIterator(windowStore.fetch(
                 2,
                 ofEpochMilli(defaultStartTime - 2L - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime - 2L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(Collections.singletonList("two")),
-            valuesToSet(windowStore.fetch(
+            valuesToSetAndCloseIterator(windowStore.fetch(
                 2,
                 ofEpochMilli(defaultStartTime - 1L - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime - 1L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(asList("two", "two+1")),
-            valuesToSet(windowStore.fetch(
+            valuesToSetAndCloseIterator(windowStore.fetch(
                 2,
                 ofEpochMilli(defaultStartTime - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(asList("two", "two+1", "two+2")),
-            valuesToSet(windowStore.fetch(
+            valuesToSetAndCloseIterator(windowStore.fetch(
                 2,
                 ofEpochMilli(defaultStartTime + 1L - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + 1L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(asList("two", "two+1", "two+2", "two+3")),
-            valuesToSet(windowStore.fetch(
+            valuesToSetAndCloseIterator(windowStore.fetch(
                 2,
                 ofEpochMilli(defaultStartTime + 2L - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + 2L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(asList("two", "two+1", "two+2", "two+3", "two+4")),
-            valuesToSet(windowStore.fetch(
+            valuesToSetAndCloseIterator(windowStore.fetch(
                 2,
                 ofEpochMilli(defaultStartTime + 3L - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + 3L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(asList("two", "two+1", "two+2", "two+3", "two+4", "two+5")),
-            valuesToSet(windowStore.fetch(
+            valuesToSetAndCloseIterator(windowStore.fetch(
                 2,
                 ofEpochMilli(defaultStartTime + 4L - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + 4L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(asList("two", "two+1", "two+2", "two+3", "two+4", "two+5", "two+6")),
-            valuesToSet(windowStore.fetch(
+            valuesToSetAndCloseIterator(windowStore.fetch(
                 2,
                 ofEpochMilli(defaultStartTime + 5L - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + 5L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(asList("two+1", "two+2", "two+3", "two+4", "two+5", "two+6")),
-            valuesToSet(windowStore.fetch(
+            valuesToSetAndCloseIterator(windowStore.fetch(
                 2,
                 ofEpochMilli(defaultStartTime + 6L - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + 6L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(asList("two+2", "two+3", "two+4", "two+5", "two+6")),
-            valuesToSet(windowStore.fetch(
+            valuesToSetAndCloseIterator(windowStore.fetch(
                 2,
                 ofEpochMilli(defaultStartTime + 7L - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + 7L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(asList("two+3", "two+4", "two+5", "two+6")),
-            valuesToSet(windowStore.fetch(
+            valuesToSetAndCloseIterator(windowStore.fetch(
                 2,
                 ofEpochMilli(defaultStartTime + 8L - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + 8L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(asList("two+4", "two+5", "two+6")),
-            valuesToSet(windowStore.fetch(
+            valuesToSetAndCloseIterator(windowStore.fetch(
                 2,
                 ofEpochMilli(defaultStartTime + 9L - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + 9L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(asList("two+5", "two+6")),
-            valuesToSet(windowStore.fetch(
+            valuesToSetAndCloseIterator(windowStore.fetch(
                 2,
                 ofEpochMilli(defaultStartTime + 10L - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + 10L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(Collections.singletonList("two+6")),
-            valuesToSet(windowStore.fetch(
+            valuesToSetAndCloseIterator(windowStore.fetch(
                 2,
                 ofEpochMilli(defaultStartTime + 11L - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + 11L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(Collections.emptyList()),
-            valuesToSet(windowStore.fetch(
+            valuesToSetAndCloseIterator(windowStore.fetch(
                 2,
                 ofEpochMilli(defaultStartTime + 12L - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + 12L + WINDOW_SIZE))));
@@ -264,14 +263,14 @@ public abstract class AbstractWindowBytesStoreTest {
 
         assertEquals(
             asList(zero, one, two, three, four, five),
-            toList(windowStore.all())
+            toListAndCloseIterator(windowStore.all())
         );
     }
 
     @Test
     public void shouldGetAllNonDeletedRecords() {
         // Add some records
-        windowStore.put(0, "zero", defaultStartTime + 0);
+        windowStore.put(0, "zero", defaultStartTime);
         windowStore.put(1, "one", defaultStartTime + 1);
         windowStore.put(2, "two", defaultStartTime + 2);
         windowStore.put(3, "three", defaultStartTime + 3);
@@ -284,7 +283,7 @@ public abstract class AbstractWindowBytesStoreTest {
         // Only non-deleted records should appear in the all() iterator
         assertEquals(
             asList(zero, two, four),
-            toList(windowStore.all())
+            toListAndCloseIterator(windowStore.all())
         );
     }
 
@@ -292,7 +291,7 @@ public abstract class AbstractWindowBytesStoreTest {
     public void shouldGetAllReturnTimestampOrderedRecords() {
         // Add some records in different order
         windowStore.put(4, "four", defaultStartTime + 4);
-        windowStore.put(0, "zero", defaultStartTime + 0);
+        windowStore.put(0, "zero", defaultStartTime);
         windowStore.put(2, "two", defaultStartTime + 2);
         windowStore.put(3, "three", defaultStartTime + 3);
         windowStore.put(1, "one", defaultStartTime + 1);
@@ -302,13 +301,13 @@ public abstract class AbstractWindowBytesStoreTest {
 
         assertEquals(
             asList(zero, one, two, three, four),
-            toList(windowStore.all())
+            toListAndCloseIterator(windowStore.all())
         );
     }
 
     @Test
     public void shouldEarlyClosedIteratorStillGetAllRecords() {
-        windowStore.put(0, "zero", defaultStartTime + 0);
+        windowStore.put(0, "zero", defaultStartTime);
         windowStore.put(1, "one", defaultStartTime + 1);
 
         final KeyValueIterator<Windowed<Integer>, String> it = windowStore.all();
@@ -318,7 +317,7 @@ public abstract class AbstractWindowBytesStoreTest {
         // A new all() iterator after a previous all() iterator was closed should return all elements.
         assertEquals(
             asList(zero, one),
-            toList(windowStore.all())
+            toListAndCloseIterator(windowStore.all())
         );
     }
 
@@ -328,7 +327,7 @@ public abstract class AbstractWindowBytesStoreTest {
 
         assertEquals(
             asList(five, four, three, two, one, zero),
-            toList(windowStore.backwardAll())
+            toListAndCloseIterator(windowStore.backwardAll())
         );
     }
 
@@ -338,15 +337,15 @@ public abstract class AbstractWindowBytesStoreTest {
 
         assertEquals(
             asList(one, two, three, four),
-            toList(windowStore.fetchAll(ofEpochMilli(defaultStartTime + 1), ofEpochMilli(defaultStartTime + 4)))
+            toListAndCloseIterator(windowStore.fetchAll(ofEpochMilli(defaultStartTime + 1), ofEpochMilli(defaultStartTime + 4)))
         );
         assertEquals(
             asList(zero, one, two, three),
-            toList(windowStore.fetchAll(ofEpochMilli(defaultStartTime), ofEpochMilli(defaultStartTime + 3)))
+            toListAndCloseIterator(windowStore.fetchAll(ofEpochMilli(defaultStartTime), ofEpochMilli(defaultStartTime + 3)))
         );
         assertEquals(
             asList(one, two, three, four, five),
-            toList(windowStore.fetchAll(ofEpochMilli(defaultStartTime + 1), ofEpochMilli(defaultStartTime + 5)))
+            toListAndCloseIterator(windowStore.fetchAll(ofEpochMilli(defaultStartTime + 1), ofEpochMilli(defaultStartTime + 5)))
         );
     }
 
@@ -356,15 +355,15 @@ public abstract class AbstractWindowBytesStoreTest {
 
         assertEquals(
             asList(four, three, two, one),
-            toList(windowStore.backwardFetchAll(ofEpochMilli(defaultStartTime + 1), ofEpochMilli(defaultStartTime + 4)))
+            toListAndCloseIterator(windowStore.backwardFetchAll(ofEpochMilli(defaultStartTime + 1), ofEpochMilli(defaultStartTime + 4)))
         );
         assertEquals(
             asList(three, two, one, zero),
-            toList(windowStore.backwardFetchAll(ofEpochMilli(defaultStartTime), ofEpochMilli(defaultStartTime + 3)))
+            toListAndCloseIterator(windowStore.backwardFetchAll(ofEpochMilli(defaultStartTime), ofEpochMilli(defaultStartTime + 3)))
         );
         assertEquals(
             asList(five, four, three, two, one),
-            toList(windowStore.backwardFetchAll(ofEpochMilli(defaultStartTime + 1), ofEpochMilli(defaultStartTime + 5)))
+            toListAndCloseIterator(windowStore.backwardFetchAll(ofEpochMilli(defaultStartTime + 1), ofEpochMilli(defaultStartTime + 5)))
         );
     }
 
@@ -374,55 +373,55 @@ public abstract class AbstractWindowBytesStoreTest {
 
         assertEquals(
             asList(zero, one),
-            toList(windowStore.fetch(
+            toListAndCloseIterator(windowStore.fetch(
                 0,
                 1,
-                ofEpochMilli(defaultStartTime + 0L - WINDOW_SIZE),
+                ofEpochMilli(defaultStartTime - WINDOW_SIZE),
-                ofEpochMilli(defaultStartTime + 0L + WINDOW_SIZE)))
+                ofEpochMilli(defaultStartTime + WINDOW_SIZE)))
         );
         assertEquals(
             Collections.singletonList(one),
-            toList(windowStore.fetch(
+            toListAndCloseIterator(windowStore.fetch(
                 1,
                 1,
-                ofEpochMilli(defaultStartTime + 0L - WINDOW_SIZE),
+                ofEpochMilli(defaultStartTime - WINDOW_SIZE),
-                ofEpochMilli(defaultStartTime + 0L + WINDOW_SIZE)))
+                ofEpochMilli(defaultStartTime + WINDOW_SIZE)))
         );
         assertEquals(
             asList(one, two, three),
-            toList(windowStore.fetch(
+            toListAndCloseIterator(windowStore.fetch(
                 1,
                 3,
-                ofEpochMilli(defaultStartTime + 0L - WINDOW_SIZE),
+                ofEpochMilli(defaultStartTime - WINDOW_SIZE),
-                ofEpochMilli(defaultStartTime + 0L + WINDOW_SIZE)))
+                ofEpochMilli(defaultStartTime + WINDOW_SIZE)))
         );
         assertEquals(
             asList(zero, one, two, three),
-            toList(windowStore.fetch(
+            toListAndCloseIterator(windowStore.fetch(
                 0,
                 5,
-                ofEpochMilli(defaultStartTime + 0L - WINDOW_SIZE),
+                ofEpochMilli(defaultStartTime - WINDOW_SIZE),
-                ofEpochMilli(defaultStartTime + 0L + WINDOW_SIZE)))
+                ofEpochMilli(defaultStartTime + WINDOW_SIZE)))
         );
         assertEquals(
             asList(zero, one, two, three, four, five),
-            toList(windowStore.fetch(
+            toListAndCloseIterator(windowStore.fetch(
                 0,
                 5,
-                ofEpochMilli(defaultStartTime + 0L - WINDOW_SIZE),
+                ofEpochMilli(defaultStartTime - WINDOW_SIZE),
-                ofEpochMilli(defaultStartTime + 0L + WINDOW_SIZE + 5L)))
+                ofEpochMilli(defaultStartTime + WINDOW_SIZE + 5L)))
         );
         assertEquals(
             asList(two, three, four, five),
-            toList(windowStore.fetch(
+            toListAndCloseIterator(windowStore.fetch(
                 0,
                 5,
                 ofEpochMilli(defaultStartTime + 2L),
-                ofEpochMilli(defaultStartTime + 0L + WINDOW_SIZE + 5L)))
+                ofEpochMilli(defaultStartTime + WINDOW_SIZE + 5L)))
         );
         assertEquals(
             Collections.emptyList(),
-            toList(windowStore.fetch(
+            toListAndCloseIterator(windowStore.fetch(
                 4,
                 5,
                 ofEpochMilli(defaultStartTime + 2L),
@@ -430,7 +429,7 @@ public abstract class AbstractWindowBytesStoreTest {
         );
         assertEquals(
             Collections.emptyList(),
-            toList(windowStore.fetch(
+            toListAndCloseIterator(windowStore.fetch(
                 0,
                 3,
                 ofEpochMilli(defaultStartTime + 3L),
@@ -438,26 +437,26 @@ public abstract class AbstractWindowBytesStoreTest {
         );
         assertEquals(
             asList(zero, one, two),
-            toList(windowStore.fetch(
+            toListAndCloseIterator(windowStore.fetch(
                 null,
                 2,
-                ofEpochMilli(defaultStartTime + 0L - WINDOW_SIZE),
+                ofEpochMilli(defaultStartTime - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + WINDOW_SIZE + 2L)))
         );
         assertEquals(
             asList(two, three, four, five),
-            toList(windowStore.fetch(
+            toListAndCloseIterator(windowStore.fetch(
                 2,
                 null,
-                ofEpochMilli(defaultStartTime + 0L - WINDOW_SIZE),
+                ofEpochMilli(defaultStartTime - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + WINDOW_SIZE + 5L)))
         );
         assertEquals(
             asList(zero, one, two, three, four, five),
-            toList(windowStore.fetch(
+            toListAndCloseIterator(windowStore.fetch(
                 null,
                 null,
-                ofEpochMilli(defaultStartTime + 0L - WINDOW_SIZE),
+                ofEpochMilli(defaultStartTime - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + WINDOW_SIZE + 5L)))
         );
     }
@@ -469,55 +468,55 @@ public abstract class AbstractWindowBytesStoreTest {
 
         assertEquals(
             asList(one, zero),
-            toList(windowStore.backwardFetch(
+            toListAndCloseIterator(windowStore.backwardFetch(
                 0,
                 1,
-                ofEpochMilli(defaultStartTime + 0L - WINDOW_SIZE),
+                ofEpochMilli(defaultStartTime - WINDOW_SIZE),
-                ofEpochMilli(defaultStartTime + 0L + WINDOW_SIZE)))
+                ofEpochMilli(defaultStartTime + WINDOW_SIZE)))
         );
         assertEquals(
             Collections.singletonList(one),
-            toList(windowStore.backwardFetch(
+            toListAndCloseIterator(windowStore.backwardFetch(
                 1,
                 1,
-                ofEpochMilli(defaultStartTime + 0L - WINDOW_SIZE),
+                ofEpochMilli(defaultStartTime - WINDOW_SIZE),
-                ofEpochMilli(defaultStartTime + 0L + WINDOW_SIZE)))
+                ofEpochMilli(defaultStartTime + WINDOW_SIZE)))
         );
         assertEquals(
             asList(three, two, one),
-            toList(windowStore.backwardFetch(
+            toListAndCloseIterator(windowStore.backwardFetch(
                 1,
                 3,
-                ofEpochMilli(defaultStartTime + 0L - WINDOW_SIZE),
+                ofEpochMilli(defaultStartTime - WINDOW_SIZE),
-                ofEpochMilli(defaultStartTime + 0L + WINDOW_SIZE)))
+                ofEpochMilli(defaultStartTime + WINDOW_SIZE)))
         );
         assertEquals(
             asList(three, two, one, zero),
-            toList(windowStore.backwardFetch(
+            toListAndCloseIterator(windowStore.backwardFetch(
                 0,
                 5,
-                ofEpochMilli(defaultStartTime + 0L - WINDOW_SIZE),
+                ofEpochMilli(defaultStartTime - WINDOW_SIZE),
-                ofEpochMilli(defaultStartTime + 0L + WINDOW_SIZE)))
+                ofEpochMilli(defaultStartTime + WINDOW_SIZE)))
         );
         assertEquals(
             asList(five, four, three, two, one, zero),
-            toList(windowStore.backwardFetch(
+            toListAndCloseIterator(windowStore.backwardFetch(
                 0,
                 5,
-                ofEpochMilli(defaultStartTime + 0L - WINDOW_SIZE),
+                ofEpochMilli(defaultStartTime - WINDOW_SIZE),
-                ofEpochMilli(defaultStartTime + 0L + WINDOW_SIZE + 5L)))
+                ofEpochMilli(defaultStartTime + WINDOW_SIZE + 5L)))
         );
         assertEquals(
             asList(five, four, three, two),
-            toList(windowStore.backwardFetch(
+            toListAndCloseIterator(windowStore.backwardFetch(
                 0,
                 5,
                 ofEpochMilli(defaultStartTime + 2L),
-                ofEpochMilli(defaultStartTime + 0L + WINDOW_SIZE + 5L)))
+                ofEpochMilli(defaultStartTime + WINDOW_SIZE + 5L)))
         );
         assertEquals(
             Collections.emptyList(),
-            toList(windowStore.backwardFetch(
+            toListAndCloseIterator(windowStore.backwardFetch(
                 4,
                 5,
                 ofEpochMilli(defaultStartTime + 2L),
@@ -525,7 +524,7 @@ public abstract class AbstractWindowBytesStoreTest {
         );
         assertEquals(
             Collections.emptyList(),
-            toList(windowStore.backwardFetch(
+            toListAndCloseIterator(windowStore.backwardFetch(
                 0,
                 3,
                 ofEpochMilli(defaultStartTime + 3L),
@@ -533,26 +532,26 @@ public abstract class AbstractWindowBytesStoreTest {
         );
         assertEquals(
             asList(two, one, zero),
-            toList(windowStore.backwardFetch(
+            toListAndCloseIterator(windowStore.backwardFetch(
                 null,
                 2,
-                ofEpochMilli(defaultStartTime + 0L - WINDOW_SIZE),
+                ofEpochMilli(defaultStartTime - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + WINDOW_SIZE + 2L)))
         );
         assertEquals(
             asList(five, four, three, two),
-            toList(windowStore.backwardFetch(
+            toListAndCloseIterator(windowStore.backwardFetch(
                 2,
                 null,
-                ofEpochMilli(defaultStartTime + 0L - WINDOW_SIZE),
+                ofEpochMilli(defaultStartTime - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + WINDOW_SIZE + 5L)))
         );
         assertEquals(
             asList(five, four, three, two, one, zero),
-            toList(windowStore.backwardFetch(
+            toListAndCloseIterator(windowStore.backwardFetch(
                 null,
                 null,
-                ofEpochMilli(defaultStartTime + 0L - WINDOW_SIZE),
+                ofEpochMilli(defaultStartTime - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + WINDOW_SIZE + 5L)))
         );
     }
@@ -563,70 +562,70 @@ public abstract class AbstractWindowBytesStoreTest {
 
         assertEquals(
             new HashSet<>(Collections.singletonList("zero")),
-            valuesToSet(windowStore.fetch(0, ofEpochMilli(defaultStartTime + 0L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 0L))));
+            valuesToSetAndCloseIterator(windowStore.fetch(0, ofEpochMilli(defaultStartTime - WINDOW_SIZE), ofEpochMilli(defaultStartTime))));
         assertEquals(
             new HashSet<>(Collections.singletonList("one")),
-            valuesToSet(windowStore.fetch(1, ofEpochMilli(defaultStartTime + 1L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 1L))));
+            valuesToSetAndCloseIterator(windowStore.fetch(1, ofEpochMilli(defaultStartTime + 1L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 1L))));
         assertEquals(
             new HashSet<>(Collections.singletonList("two")),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 2L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 2L))));
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 2L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 2L))));
         assertEquals(
             new HashSet<>(Collections.singletonList("three")),
-            valuesToSet(windowStore.fetch(3, ofEpochMilli(defaultStartTime + 3L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 3L))));
+            valuesToSetAndCloseIterator(windowStore.fetch(3, ofEpochMilli(defaultStartTime + 3L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 3L))));
         assertEquals(
             new HashSet<>(Collections.singletonList("four")),
-            valuesToSet(windowStore.fetch(4, ofEpochMilli(defaultStartTime + 4L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 4L))));
+            valuesToSetAndCloseIterator(windowStore.fetch(4, ofEpochMilli(defaultStartTime + 4L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 4L))));
         assertEquals(
             new HashSet<>(Collections.singletonList("five")),
-            valuesToSet(windowStore.fetch(5, ofEpochMilli(defaultStartTime + 5L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 5L))));
+            valuesToSetAndCloseIterator(windowStore.fetch(5, ofEpochMilli(defaultStartTime + 5L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 5L))));
 
-        putSecondBatch(windowStore, defaultStartTime, context);
+        putSecondBatch(windowStore, defaultStartTime);
 
         assertEquals(
             new HashSet<>(Collections.emptyList()),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime - 1L - WINDOW_SIZE), ofEpochMilli(defaultStartTime - 1L))));
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime - 1L - WINDOW_SIZE), ofEpochMilli(defaultStartTime - 1L))));
         assertEquals(
             new HashSet<>(Collections.emptyList()),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 0L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 0L))));
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime - WINDOW_SIZE), ofEpochMilli(defaultStartTime))));
         assertEquals(
             new HashSet<>(Collections.emptyList()),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 1L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 1L))));
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 1L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 1L))));
         assertEquals(
             new HashSet<>(Collections.singletonList("two")),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 2L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 2L))));
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 2L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 2L))));
         assertEquals(
             new HashSet<>(asList("two", "two+1")),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 3L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 3L))));
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 3L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 3L))));
         assertEquals(
             new HashSet<>(asList("two", "two+1", "two+2")),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 4L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 4L))));
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 4L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 4L))));
         assertEquals(
             new HashSet<>(asList("two", "two+1", "two+2", "two+3")),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 5L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 5L))));
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 5L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 5L))));
         assertEquals(
             new HashSet<>(asList("two+1", "two+2", "two+3", "two+4")),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 6L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 6L))));
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 6L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 6L))));
         assertEquals(
             new HashSet<>(asList("two+2", "two+3", "two+4", "two+5")),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 7L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 7L))));
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 7L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 7L))));
         assertEquals(
             new HashSet<>(asList("two+3", "two+4", "two+5", "two+6")),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 8L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 8L))));
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 8L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 8L))));
         assertEquals(
             new HashSet<>(asList("two+4", "two+5", "two+6")),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 9L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 9L))));
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 9L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 9L))));
         assertEquals(
             new HashSet<>(asList("two+5", "two+6")),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 10L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 10L))));
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 10L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 10L))));
         assertEquals(
             new HashSet<>(Collections.singletonList("two+6")),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 11L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 11L))));
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 11L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 11L))));
         assertEquals(
             new HashSet<>(Collections.emptyList()),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 12L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 12L))));
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 12L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 12L))));
         assertEquals(
             new HashSet<>(Collections.emptyList()),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 13L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 13L))));
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 13L - WINDOW_SIZE), ofEpochMilli(defaultStartTime + 13L))));
 
         // Flush the store and verify all current entries were properly flushed ...
         windowStore.flush();
@@ -652,90 +651,90 @@ public abstract class AbstractWindowBytesStoreTest {
 
         assertEquals(
             new HashSet<>(Collections.singletonList("zero")),
-            valuesToSet(windowStore.fetch(0, ofEpochMilli(defaultStartTime + 0L),
+            valuesToSetAndCloseIterator(windowStore.fetch(0, ofEpochMilli(defaultStartTime),
-                ofEpochMilli(defaultStartTime + 0L + WINDOW_SIZE))));
+                ofEpochMilli(defaultStartTime + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(Collections.singletonList("one")),
-            valuesToSet(windowStore.fetch(1, ofEpochMilli(defaultStartTime + 1L),
+            valuesToSetAndCloseIterator(windowStore.fetch(1, ofEpochMilli(defaultStartTime + 1L),
                 ofEpochMilli(defaultStartTime + 1L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(Collections.singletonList("two")),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 2L),
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 2L),
                 ofEpochMilli(defaultStartTime + 2L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(Collections.emptyList()),
-            valuesToSet(windowStore.fetch(3, ofEpochMilli(defaultStartTime + 3L),
+            valuesToSetAndCloseIterator(windowStore.fetch(3, ofEpochMilli(defaultStartTime + 3L),
                 ofEpochMilli(defaultStartTime + 3L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(Collections.singletonList("four")),
-            valuesToSet(windowStore.fetch(4, ofEpochMilli(defaultStartTime + 4L),
+            valuesToSetAndCloseIterator(windowStore.fetch(4, ofEpochMilli(defaultStartTime + 4L),
                 ofEpochMilli(defaultStartTime + 4L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(Collections.singletonList("five")),
-            valuesToSet(windowStore.fetch(5, ofEpochMilli(defaultStartTime + 5L),
+            valuesToSetAndCloseIterator(windowStore.fetch(5, ofEpochMilli(defaultStartTime + 5L),
                 ofEpochMilli(defaultStartTime + 5L + WINDOW_SIZE))));
 
-        putSecondBatch(windowStore, defaultStartTime, context);
+        putSecondBatch(windowStore, defaultStartTime);
 
         assertEquals(
             new HashSet<>(Collections.emptyList()),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime - 2L),
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime - 2L),
                 ofEpochMilli(defaultStartTime - 2L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(Collections.singletonList("two")),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime - 1L),
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime - 1L),
                 ofEpochMilli(defaultStartTime - 1L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(asList("two", "two+1")),
-            valuesToSet(windowStore
+            valuesToSetAndCloseIterator(windowStore
                 .fetch(2, ofEpochMilli(defaultStartTime), ofEpochMilli(defaultStartTime + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(asList("two", "two+1", "two+2")),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 1L),
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 1L),
                 ofEpochMilli(defaultStartTime + 1L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(asList("two", "two+1", "two+2", "two+3")),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 2L),
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 2L),
                 ofEpochMilli(defaultStartTime + 2L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(asList("two+1", "two+2", "two+3", "two+4")),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 3L),
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 3L),
                 ofEpochMilli(defaultStartTime + 3L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(asList("two+2", "two+3", "two+4", "two+5")),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 4L),
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 4L),
                 ofEpochMilli(defaultStartTime + 4L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(asList("two+3", "two+4", "two+5", "two+6")),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 5L),
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 5L),
                 ofEpochMilli(defaultStartTime + 5L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(asList("two+4", "two+5", "two+6")),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 6L),
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 6L),
                 ofEpochMilli(defaultStartTime + 6L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(asList("two+5", "two+6")),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 7L),
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 7L),
                 ofEpochMilli(defaultStartTime + 7L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(Collections.singletonList("two+6")),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 8L),
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 8L),
                 ofEpochMilli(defaultStartTime + 8L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(Collections.emptyList()),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 9L),
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 9L),
                 ofEpochMilli(defaultStartTime + 9L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(Collections.emptyList()),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 10L),
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 10L),
                 ofEpochMilli(defaultStartTime + 10L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(Collections.emptyList()),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 11L),
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 11L),
                 ofEpochMilli(defaultStartTime + 11L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(Collections.emptyList()),
-            valuesToSet(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 12L),
+            valuesToSetAndCloseIterator(windowStore.fetch(2, ofEpochMilli(defaultStartTime + 12L),
                 ofEpochMilli(defaultStartTime + 12L + WINDOW_SIZE))));
 
         // Flush the store and verify all current entries were properly flushed ...
@@ -763,13 +762,13 @@ public abstract class AbstractWindowBytesStoreTest {
     public void testPutSameKeyTimestamp() {
         windowStore.close();
         windowStore = buildWindowStore(RETENTION_PERIOD, WINDOW_SIZE, true, Serdes.Integer(), Serdes.String());
-        windowStore.init((StateStoreContext) context, windowStore);
+        windowStore.init(context, windowStore);
 
         windowStore.put(0, "zero", defaultStartTime);
 
         assertEquals(
             new HashSet<>(Collections.singletonList("zero")),
-            valuesToSet(windowStore.fetch(0, ofEpochMilli(defaultStartTime - WINDOW_SIZE),
+            valuesToSetAndCloseIterator(windowStore.fetch(0, ofEpochMilli(defaultStartTime - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + WINDOW_SIZE))));
 
         windowStore.put(0, "zero", defaultStartTime);
@@ -778,31 +777,31 @@ public abstract class AbstractWindowBytesStoreTest {
 
         assertEquals(
             new HashSet<>(asList("zero", "zero", "zero+", "zero++")),
-            valuesToSet(windowStore.fetch(
+            valuesToSetAndCloseIterator(windowStore.fetch(
                 0,
                 ofEpochMilli(defaultStartTime - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(asList("zero", "zero", "zero+", "zero++")),
-            valuesToSet(windowStore.fetch(
+            valuesToSetAndCloseIterator(windowStore.fetch(
                 0,
                 ofEpochMilli(defaultStartTime + 1L - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + 1L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(asList("zero", "zero", "zero+", "zero++")),
-            valuesToSet(windowStore.fetch(
+            valuesToSetAndCloseIterator(windowStore.fetch(
                 0,
                 ofEpochMilli(defaultStartTime + 2L - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + 2L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(asList("zero", "zero", "zero+", "zero++")),
-            valuesToSet(windowStore.fetch(
+            valuesToSetAndCloseIterator(windowStore.fetch(
                 0,
                 ofEpochMilli(defaultStartTime + 3L - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + 3L + WINDOW_SIZE))));
         assertEquals(
             new HashSet<>(Collections.emptyList()),
-            valuesToSet(windowStore.fetch(
+            valuesToSetAndCloseIterator(windowStore.fetch(
                 0,
                 ofEpochMilli(defaultStartTime + 4L - WINDOW_SIZE),
                 ofEpochMilli(defaultStartTime + 4L + WINDOW_SIZE))));
@@ -845,7 +844,7 @@ public abstract class AbstractWindowBytesStoreTest {
             Serdes.String(),
             Serdes.String());
 
-        windowStore.init((StateStoreContext) context, windowStore);
+        windowStore.init(context, windowStore);
 
         windowStore.put("a", "0001", 0);
         windowStore.put("aa", "0002", 0);
@@ -855,7 +854,7 @@ public abstract class AbstractWindowBytesStoreTest {
 
         final Set<String> expected = new HashSet<>(asList("0001", "0003", "0005"));
         assertThat(
-            valuesToSet(windowStore.fetch("a", ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE))),
+            valuesToSetAndCloseIterator(windowStore.fetch("a", ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE))),
             equalTo(expected)
         );
 
@@ -887,12 +886,14 @@ public abstract class AbstractWindowBytesStoreTest {
         windowStore.put(1, "one", currentTime);
         windowStore.put(1, "one v2", currentTime);
 
-        WindowStoreIterator<String> iterator = windowStore.fetch(1, 0, currentTime);
+        try (final WindowStoreIterator<String> iterator = windowStore.fetch(1, 0, currentTime)) {
-        assertEquals(new KeyValue<>(currentTime, "one v2"), iterator.next());
+            assertEquals(new KeyValue<>(currentTime, "one v2"), iterator.next());
+        }
 
         windowStore.put(1, null, currentTime);
-        iterator = windowStore.fetch(1, 0, currentTime);
+        try (final WindowStoreIterator<String> iterator = windowStore.fetch(1, 0, currentTime)) {
-        assertFalse(iterator.hasNext());
+            assertFalse(iterator.hasNext());
+        }
     }
 
     @Test
@@ -905,6 +906,7 @@ public abstract class AbstractWindowBytesStoreTest {
         assertThrows(NullPointerException.class, () -> windowStore.put(null, "anyValue", 0L));
     }
 
+    @SuppressWarnings("resource")
     @Test
     public void shouldThrowNullPointerExceptionOnGetNullKey() {
         assertThrows(NullPointerException.class, () -> windowStore.fetch(null, ofEpochMilli(1L), ofEpochMilli(2L)));
@@ -917,7 +919,7 @@ public abstract class AbstractWindowBytesStoreTest {
             true,
             Serdes.Bytes(),
             Serdes.String());
-        windowStore.init((StateStoreContext) context, windowStore);
+        windowStore.init(context, windowStore);
 
         final Bytes key1 = Bytes.wrap(new byte[] {0});
         final Bytes key2 = Bytes.wrap(new byte[] {0, 0});
@@ -934,17 +936,17 @@ public abstract class AbstractWindowBytesStoreTest {
 
         final Set<String> expectedKey1 = new HashSet<>(asList("1", "4", "7"));
         assertThat(
-            valuesToSet(windowStore.fetch(key1, ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE))),
+            valuesToSetAndCloseIterator(windowStore.fetch(key1, ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE))),
             equalTo(expectedKey1)
         );
         final Set<String> expectedKey2 = new HashSet<>(asList("2", "5", "8"));
         assertThat(
-            valuesToSet(windowStore.fetch(key2, ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE))),
+            valuesToSetAndCloseIterator(windowStore.fetch(key2, ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE))),
             equalTo(expectedKey2)
         );
         final Set<String> expectedKey3 = new HashSet<>(asList("3", "6", "9"));
         assertThat(
-            valuesToSet(windowStore.fetch(key3, ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE))),
+            valuesToSetAndCloseIterator(windowStore.fetch(key3, ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE))),
             equalTo(expectedKey3)
         );
 
@@ -990,7 +992,7 @@ public abstract class AbstractWindowBytesStoreTest {
         final Properties streamsConfig = StreamsTestUtils.getStreamsConfig();
         final WindowStore<Integer, String> windowStore =
             buildWindowStore(RETENTION_PERIOD, WINDOW_SIZE, false, Serdes.Integer(), Serdes.String());
-        final InternalMockProcessorContext context = new InternalMockProcessorContext(
+        final InternalMockProcessorContext<?, ?> context = new InternalMockProcessorContext<>(
             TestUtils.tempDirectory(),
             new StreamsConfig(streamsConfig),
             recordCollector
@@ -998,7 +1000,7 @@ public abstract class AbstractWindowBytesStoreTest {
         final Time time = Time.SYSTEM;
         context.setSystemTimeMs(time.milliseconds());
         context.setTime(1L);
-        windowStore.init((StateStoreContext) context, windowStore);
+        windowStore.init(context, windowStore);
 
         // Advance stream time by inserting record with large enough timestamp that records with timestamp 0 are expired
         windowStore.put(1, "initial record", 2 * RETENTION_PERIOD);
@@ -1108,7 +1110,7 @@ public abstract class AbstractWindowBytesStoreTest {
     public void testFetchDuplicates() {
         windowStore.close();
         windowStore = buildWindowStore(RETENTION_PERIOD, WINDOW_SIZE, true, Serdes.Integer(), Serdes.String());
-        windowStore.init((StateStoreContext) context, windowStore);
+        windowStore.init(context, windowStore);
 
         long currentTime = 0;
         windowStore.put(1, "one", currentTime);
@@ -1135,7 +1137,7 @@ public abstract class AbstractWindowBytesStoreTest {
 
     private void putFirstBatch(final WindowStore<Integer, String> store,
                                @SuppressWarnings("SameParameterValue") final long startTime,
-                               final InternalMockProcessorContext context) {
+                               final InternalMockProcessorContext<?, ?> context) {
         context.setRecordContext(createRecordContext(startTime));
         store.put(0, "zero", startTime);
         store.put(1, "one", startTime + 1L);
@@ -1146,8 +1148,7 @@ public abstract class AbstractWindowBytesStoreTest {
     }
 
     private void putSecondBatch(final WindowStore<Integer, String> store,
-                                @SuppressWarnings("SameParameterValue") final long startTime,
+                                @SuppressWarnings("SameParameterValue") final long startTime) {
-                                final InternalMockProcessorContext context) {
         store.put(2, "two+1", startTime + 3L);
         store.put(2, "two+2", startTime + 4L);
         store.put(2, "two+3", startTime + 5L);

streams/src/test/java/org/apache/kafka/streams/state/internals/CachingInMemorySessionStoreTest.java

@@ -60,7 +60,7 @@ import java.util.Random;
 import static java.util.Arrays.asList;
 import static org.apache.kafka.common.utils.Utils.mkEntry;
 import static org.apache.kafka.common.utils.Utils.mkMap;
-import static org.apache.kafka.test.StreamsTestUtils.toList;
+import static org.apache.kafka.test.StreamsTestUtils.toListAndCloseIterator;
 import static org.apache.kafka.test.StreamsTestUtils.verifyKeyValueList;
 import static org.apache.kafka.test.StreamsTestUtils.verifyWindowedKeyValue;
 import static org.hamcrest.CoreMatchers.hasItem;
@@ -401,7 +401,7 @@ public class CachingInMemorySessionStoreTest {
         // add one that shouldn't appear in the results
         cachingStore.put(new Windowed<>(keyAA, new SessionWindow(0, 0)), "5".getBytes());
 
-        final List<KeyValue<Windowed<Bytes>, byte[]>> results = toList(cachingStore.fetch(keyA));
+        final List<KeyValue<Windowed<Bytes>, byte[]>> results = toListAndCloseIterator(cachingStore.fetch(keyA));
         verifyKeyValueList(expected, results);
     }
 
@@ -420,7 +420,7 @@ public class CachingInMemorySessionStoreTest {
         // add one that shouldn't appear in the results
         cachingStore.put(new Windowed<>(keyAA, new SessionWindow(0, 0)), "5".getBytes());
 
-        final List<KeyValue<Windowed<Bytes>, byte[]>> results = toList(cachingStore.backwardFetch(keyA));
+        final List<KeyValue<Windowed<Bytes>, byte[]>> results = toListAndCloseIterator(cachingStore.backwardFetch(keyA));
         Collections.reverse(results);
         verifyKeyValueList(expected, results);
     }
@@ -439,7 +439,7 @@ public class CachingInMemorySessionStoreTest {
     @Test
     public void shouldQueryItemsInCacheAndStore() {
         final List<KeyValue<Windowed<Bytes>, byte[]>> added = addSessionsUntilOverflow("a");
-        final List<KeyValue<Windowed<Bytes>, byte[]>> actual = toList(cachingStore.findSessions(
+        final List<KeyValue<Windowed<Bytes>, byte[]>> actual = toListAndCloseIterator(cachingStore.findSessions(
                 Bytes.wrap("a".getBytes(StandardCharsets.UTF_8)),
                 0,
                 added.size() * 10L));

streams/src/test/java/org/apache/kafka/streams/state/internals/CachingPersistentSessionStoreTest.java

@@ -60,7 +60,7 @@ import java.util.Random;
 import static java.util.Arrays.asList;
 import static org.apache.kafka.common.utils.Utils.mkEntry;
 import static org.apache.kafka.common.utils.Utils.mkMap;
-import static org.apache.kafka.test.StreamsTestUtils.toList;
+import static org.apache.kafka.test.StreamsTestUtils.toListAndCloseIterator;
 import static org.apache.kafka.test.StreamsTestUtils.verifyKeyValueList;
 import static org.apache.kafka.test.StreamsTestUtils.verifyWindowedKeyValue;
 import static org.hamcrest.CoreMatchers.hasItem;
@@ -409,7 +409,7 @@ public class CachingPersistentSessionStoreTest {
         // add one that shouldn't appear in the results
         cachingStore.put(new Windowed<>(keyAA, new SessionWindow(0, 0)), "5".getBytes());
 
-        final List<KeyValue<Windowed<Bytes>, byte[]>> results = toList(cachingStore.fetch(keyA));
+        final List<KeyValue<Windowed<Bytes>, byte[]>> results = toListAndCloseIterator(cachingStore.fetch(keyA));
         verifyKeyValueList(expected, results);
     }
 
@@ -428,7 +428,7 @@ public class CachingPersistentSessionStoreTest {
         // add one that shouldn't appear in the results
         cachingStore.put(new Windowed<>(keyAA, new SessionWindow(0, 0)), "5".getBytes());
 
-        final List<KeyValue<Windowed<Bytes>, byte[]>> results = toList(cachingStore.backwardFetch(keyA));
+        final List<KeyValue<Windowed<Bytes>, byte[]>> results = toListAndCloseIterator(cachingStore.backwardFetch(keyA));
         Collections.reverse(results);
         verifyKeyValueList(expected, results);
     }
@@ -448,7 +448,7 @@ public class CachingPersistentSessionStoreTest {
     @Test
     public void shouldQueryItemsInCacheAndStore() {
         final List<KeyValue<Windowed<Bytes>, byte[]>> added = addSessionsUntilOverflow("a");
-        final List<KeyValue<Windowed<Bytes>, byte[]>> actual = toList(cachingStore.findSessions(
+        final List<KeyValue<Windowed<Bytes>, byte[]>> actual = toListAndCloseIterator(cachingStore.findSessions(
                 Bytes.wrap("a".getBytes(StandardCharsets.UTF_8)),
                 0,
                 added.size() * 10L

streams/src/test/java/org/apache/kafka/streams/state/internals/CachingPersistentWindowStoreTest.java

@@ -73,7 +73,7 @@ import static java.util.Arrays.asList;
 import static org.apache.kafka.common.utils.Utils.mkEntry;
 import static org.apache.kafka.common.utils.Utils.mkMap;
 import static org.apache.kafka.streams.state.internals.ThreadCacheTest.memoryCacheEntrySize;
-import static org.apache.kafka.test.StreamsTestUtils.toList;
+import static org.apache.kafka.test.StreamsTestUtils.toListAndCloseIterator;
 import static org.apache.kafka.test.StreamsTestUtils.verifyAllWindowedKeyValues;
 import static org.apache.kafka.test.StreamsTestUtils.verifyKeyValueList;
 import static org.apache.kafka.test.StreamsTestUtils.verifyWindowedKeyValue;
@@ -844,7 +844,7 @@ public class CachingPersistentWindowStoreTest {
             KeyValue.pair(SEGMENT_INTERVAL, bytesValue("0005"))
         );
         final List<KeyValue<Long, byte[]>> actual =
-            toList(cachingStore.fetch(bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)));
+            toListAndCloseIterator(cachingStore.fetch(bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)));
         verifyKeyValueList(expected, actual);
     }
 
@@ -862,7 +862,7 @@ public class CachingPersistentWindowStoreTest {
             KeyValue.pair(0L, bytesValue("0001"))
         );
         final List<KeyValue<Long, byte[]>> actual =
-            toList(cachingStore.backwardFetch(bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)));
+            toListAndCloseIterator(cachingStore.backwardFetch(bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)));
         verifyKeyValueList(expected, actual);
     }
 
@@ -880,14 +880,14 @@ public class CachingPersistentWindowStoreTest {
                 windowedPair("a", "0003", 1),
                 windowedPair("a", "0005", SEGMENT_INTERVAL)
             ),
-            toList(cachingStore.fetch(bytesKey("a"), bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
+            toListAndCloseIterator(cachingStore.fetch(bytesKey("a"), bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
         );
 
         verifyKeyValueList(
             asList(
                 windowedPair("aa", "0002", 0),
                 windowedPair("aa", "0004", 1)),
-            toList(cachingStore.fetch(bytesKey("aa"), bytesKey("aa"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
+            toListAndCloseIterator(cachingStore.fetch(bytesKey("aa"), bytesKey("aa"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
         );
 
         verifyKeyValueList(
@@ -898,7 +898,7 @@ public class CachingPersistentWindowStoreTest {
                 windowedPair("aa", "0004", 1),
                 windowedPair("a", "0005", SEGMENT_INTERVAL)
             ),
-            toList(cachingStore.fetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
+            toListAndCloseIterator(cachingStore.fetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
         );
     }
 
@@ -916,14 +916,14 @@ public class CachingPersistentWindowStoreTest {
                 windowedPair("a", "0003", 1),
                 windowedPair("a", "0001", 0)
             ),
-            toList(cachingStore.backwardFetch(bytesKey("a"), bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
+            toListAndCloseIterator(cachingStore.backwardFetch(bytesKey("a"), bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
         );
 
         verifyKeyValueList(
             asList(
                 windowedPair("aa", "0004", 1),
                 windowedPair("aa", "0002", 0)),
-            toList(cachingStore.backwardFetch(bytesKey("aa"), bytesKey("aa"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
+            toListAndCloseIterator(cachingStore.backwardFetch(bytesKey("aa"), bytesKey("aa"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
         );
 
         verifyKeyValueList(
@@ -934,7 +934,7 @@ public class CachingPersistentWindowStoreTest {
                 windowedPair("a", "0003", 1),
                 windowedPair("a", "0001", 0)
             ),
-            toList(cachingStore.backwardFetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
+            toListAndCloseIterator(cachingStore.backwardFetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
         );
     }
 

streams/src/test/java/org/apache/kafka/streams/state/internals/CompositeReadOnlyKeyValueStoreTest.java

@@ -43,7 +43,7 @@ import java.util.NoSuchElementException;
 
 import static java.util.Arrays.asList;
 import static java.util.Collections.singletonList;
-import static org.apache.kafka.test.StreamsTestUtils.toList;
+import static org.apache.kafka.test.StreamsTestUtils.toListAndCloseIterator;
 import static org.junit.jupiter.api.Assertions.assertArrayEquals;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNull;
@@ -276,7 +276,7 @@ public class CompositeReadOnlyKeyValueStoreTest {
         stubOneUnderlying.put("b", "b");
         stubOneUnderlying.put("c", "c");
 
-        final List<KeyValue<String, String>> results = toList(theStore.range("a", "b"));
+        final List<KeyValue<String, String>> results = toListAndCloseIterator(theStore.range("a", "b"));
         assertTrue(results.contains(new KeyValue<>("a", "a")));
         assertTrue(results.contains(new KeyValue<>("b", "b")));
         assertEquals(2, results.size());
@@ -288,7 +288,7 @@ public class CompositeReadOnlyKeyValueStoreTest {
         stubOneUnderlying.put("b", "b");
         stubOneUnderlying.put("c", "c");
 
-        final List<KeyValue<String, String>> results = toList(theStore.reverseRange("a", "b"));
+        final List<KeyValue<String, String>> results = toListAndCloseIterator(theStore.reverseRange("a", "b"));
         assertArrayEquals(
             asList(
                 new KeyValue<>("b", "b"),
@@ -303,7 +303,7 @@ public class CompositeReadOnlyKeyValueStoreTest {
         stubOneUnderlying.put("abcd", "b");
         stubOneUnderlying.put("abce", "c");
 
-        final List<KeyValue<String, String>> results = toList(theStore.prefixScan("abcd", new StringSerializer()));
+        final List<KeyValue<String, String>> results = toListAndCloseIterator(theStore.prefixScan("abcd", new StringSerializer()));
         assertTrue(results.contains(new KeyValue<>("abcd", "b")));
         assertEquals(1, results.size());
     }
@@ -314,7 +314,7 @@ public class CompositeReadOnlyKeyValueStoreTest {
         stubOneUnderlying.put("aa", "b");
         stubOneUnderlying.put("b", "c");
 
-        final List<KeyValue<String, String>> results = toList(theStore.prefixScan("a", new StringSerializer()));
+        final List<KeyValue<String, String>> results = toListAndCloseIterator(theStore.prefixScan("a", new StringSerializer()));
         assertTrue(results.contains(new KeyValue<>("a", "a")));
         assertTrue(results.contains(new KeyValue<>("aa", "b")));
         assertEquals(2, results.size());
@@ -333,7 +333,7 @@ public class CompositeReadOnlyKeyValueStoreTest {
         cache.put("d", "d");
         cache.put("x", "x");
 
-        final List<KeyValue<String, String>> results = toList(theStore.range("a", "e"));
+        final List<KeyValue<String, String>> results = toListAndCloseIterator(theStore.range("a", "e"));
         assertArrayEquals(
             asList(
                 new KeyValue<>("a", "a"),
@@ -357,7 +357,7 @@ public class CompositeReadOnlyKeyValueStoreTest {
         cache.put("ab", "d");
         cache.put("x", "x");
 
-        final List<KeyValue<String, String>> results = toList(theStore.prefixScan("a", new StringSerializer()));
+        final List<KeyValue<String, String>> results = toListAndCloseIterator(theStore.prefixScan("a", new StringSerializer()));
         assertArrayEquals(
             asList(
                 new KeyValue<>("a", "a"),
@@ -380,7 +380,7 @@ public class CompositeReadOnlyKeyValueStoreTest {
         cache.put("d", "d");
         cache.put("x", "x");
 
-        final List<KeyValue<String, String>> results = toList(theStore.reverseRange("a", "e"));
+        final List<KeyValue<String, String>> results = toListAndCloseIterator(theStore.reverseRange("a", "e"));
         assertTrue(results.contains(new KeyValue<>("a", "a")));
         assertTrue(results.contains(new KeyValue<>("b", "b")));
         assertTrue(results.contains(new KeyValue<>("c", "c")));
@@ -401,7 +401,7 @@ public class CompositeReadOnlyKeyValueStoreTest {
         cache.put("d", "d");
         cache.put("x", "x");
 
-        final List<KeyValue<String, String>> results = toList(theStore.all());
+        final List<KeyValue<String, String>> results = toListAndCloseIterator(theStore.all());
         assertTrue(results.contains(new KeyValue<>("a", "a")));
         assertTrue(results.contains(new KeyValue<>("b", "b")));
         assertTrue(results.contains(new KeyValue<>("c", "c")));
@@ -424,7 +424,7 @@ public class CompositeReadOnlyKeyValueStoreTest {
         cache.put("d", "d");
         cache.put("x", "x");
 
-        final List<KeyValue<String, String>> results = toList(theStore.reverseAll());
+        final List<KeyValue<String, String>> results = toListAndCloseIterator(theStore.reverseAll());
         assertTrue(results.contains(new KeyValue<>("a", "a")));
         assertTrue(results.contains(new KeyValue<>("b", "b")));
         assertTrue(results.contains(new KeyValue<>("c", "c")));

streams/src/test/java/org/apache/kafka/streams/state/internals/CompositeReadOnlySessionStoreTest.java

@@ -36,7 +36,7 @@ import java.util.Arrays;
 import java.util.List;
 
 import static java.util.Collections.singletonList;
-import static org.apache.kafka.test.StreamsTestUtils.toList;
+import static org.apache.kafka.test.StreamsTestUtils.toListAndCloseIterator;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.core.IsEqual.equalTo;
 import static org.junit.jupiter.api.Assertions.assertEquals;
@@ -69,7 +69,7 @@ public class CompositeReadOnlySessionStoreTest {
         underlyingSessionStore.put(new Windowed<>("a", new SessionWindow(0, 0)), 1L);
         underlyingSessionStore.put(new Windowed<>("a", new SessionWindow(10, 10)), 2L);
 
-        final List<KeyValue<Windowed<String>, Long>> results = toList(sessionStore.fetch("a"));
+        final List<KeyValue<Windowed<String>, Long>> results = toListAndCloseIterator(sessionStore.fetch("a"));
         assertEquals(Arrays.asList(KeyValue.pair(new Windowed<>("a", new SessionWindow(0, 0)), 1L),
                                    KeyValue.pair(new Windowed<>("a", new SessionWindow(10, 10)), 2L)),
                      results);
@@ -93,8 +93,8 @@ public class CompositeReadOnlySessionStoreTest {
         underlyingSessionStore.put(keyOne, 0L);
         secondUnderlying.put(keyTwo, 10L);
 
-        final List<KeyValue<Windowed<String>, Long>> keyOneResults = toList(sessionStore.fetch("key-one"));
+        final List<KeyValue<Windowed<String>, Long>> keyOneResults = toListAndCloseIterator(sessionStore.fetch("key-one"));
-        final List<KeyValue<Windowed<String>, Long>> keyTwoResults = toList(sessionStore.fetch("key-two"));
+        final List<KeyValue<Windowed<String>, Long>> keyTwoResults = toListAndCloseIterator(sessionStore.fetch("key-two"));
 
         assertEquals(singletonList(KeyValue.pair(keyOne, 0L)), keyOneResults);
         assertEquals(singletonList(KeyValue.pair(keyTwo, 10L)), keyTwoResults);
@@ -146,7 +146,7 @@ public class CompositeReadOnlySessionStoreTest {
         stubProviderTwo.addStore(storeName, secondUnderlying);
         underlyingSessionStore.put(new Windowed<>("a", new SessionWindow(0, 0)), 0L);
         secondUnderlying.put(new Windowed<>("b", new SessionWindow(0, 0)), 10L);
-        final List<KeyValue<Windowed<String>, Long>> results = StreamsTestUtils.toList(sessionStore.fetch("a", "b"));
+        final List<KeyValue<Windowed<String>, Long>> results = StreamsTestUtils.toListAndCloseIterator(sessionStore.fetch("a", "b"));
         assertThat(results, equalTo(Arrays.asList(
             KeyValue.pair(new Windowed<>("a", new SessionWindow(0, 0)), 0L),
             KeyValue.pair(new Windowed<>("b", new SessionWindow(0, 0)), 10L))));
@@ -159,7 +159,7 @@ public class CompositeReadOnlySessionStoreTest {
         stubProviderTwo.addStore(storeName, secondUnderlying);
         underlyingSessionStore.put(new Windowed<>("a", new SessionWindow(0, 0)), 0L);
         secondUnderlying.put(new Windowed<>("b", new SessionWindow(0, 0)), 10L);
-        final List<KeyValue<Windowed<String>, Long>> results = StreamsTestUtils.toList(sessionStore.fetch(null, "b"));
+        final List<KeyValue<Windowed<String>, Long>> results = StreamsTestUtils.toListAndCloseIterator(sessionStore.fetch(null, "b"));
         assertThat(results, equalTo(Arrays.asList(
             KeyValue.pair(new Windowed<>("a", new SessionWindow(0, 0)), 0L),
             KeyValue.pair(new Windowed<>("b", new SessionWindow(0, 0)), 10L))));
@@ -172,7 +172,7 @@ public class CompositeReadOnlySessionStoreTest {
         stubProviderTwo.addStore(storeName, secondUnderlying);
         underlyingSessionStore.put(new Windowed<>("a", new SessionWindow(0, 0)), 0L);
         secondUnderlying.put(new Windowed<>("b", new SessionWindow(0, 0)), 10L);
-        final List<KeyValue<Windowed<String>, Long>> results = StreamsTestUtils.toList(sessionStore.fetch("a", null));
+        final List<KeyValue<Windowed<String>, Long>> results = StreamsTestUtils.toListAndCloseIterator(sessionStore.fetch("a", null));
         assertThat(results, equalTo(Arrays.asList(
             KeyValue.pair(new Windowed<>("a", new SessionWindow(0, 0)), 0L),
             KeyValue.pair(new Windowed<>("b", new SessionWindow(0, 0)), 10L))));
@@ -185,7 +185,7 @@ public class CompositeReadOnlySessionStoreTest {
         stubProviderTwo.addStore(storeName, secondUnderlying);
         underlyingSessionStore.put(new Windowed<>("a", new SessionWindow(0, 0)), 0L);
         secondUnderlying.put(new Windowed<>("b", new SessionWindow(0, 0)), 10L);
-        final List<KeyValue<Windowed<String>, Long>> results = StreamsTestUtils.toList(sessionStore.fetch(null, null));
+        final List<KeyValue<Windowed<String>, Long>> results = StreamsTestUtils.toListAndCloseIterator(sessionStore.fetch(null, null));
         assertThat(results, equalTo(Arrays.asList(
             KeyValue.pair(new Windowed<>("a", new SessionWindow(0, 0)), 0L),
             KeyValue.pair(new Windowed<>("b", new SessionWindow(0, 0)), 10L))));

streams/src/test/java/org/apache/kafka/streams/state/internals/CompositeReadOnlyWindowStoreTest.java

@@ -90,7 +90,7 @@ public class CompositeReadOnlyWindowStoreTest {
 
         assertEquals(
                 asList(new KeyValue<>(0L, "my-value"), new KeyValue<>(10L, "my-later-value")),
-                StreamsTestUtils.toList(windowStore.fetch("my-key", ofEpochMilli(0L), ofEpochMilli(25L)))
+                StreamsTestUtils.toListAndCloseIterator(windowStore.fetch("my-key", ofEpochMilli(0L), ofEpochMilli(25L)))
         );
     }
 
@@ -102,7 +102,7 @@ public class CompositeReadOnlyWindowStoreTest {
 
         assertEquals(
                 asList(new KeyValue<>(10L, "my-later-value"), new KeyValue<>(0L, "my-value")),
-                StreamsTestUtils.toList(windowStore.backwardFetch("my-key", ofEpochMilli(0L), ofEpochMilli(25L)))
+                StreamsTestUtils.toListAndCloseIterator(windowStore.backwardFetch("my-key", ofEpochMilli(0L), ofEpochMilli(25L)))
         );
     }
 
@@ -132,9 +132,9 @@ public class CompositeReadOnlyWindowStoreTest {
         secondUnderlying.put("key-two", "value-two", 10L);
 
         final List<KeyValue<Long, String>> keyOneResults =
-            StreamsTestUtils.toList(windowStore.fetch("key-one", ofEpochMilli(0L), ofEpochMilli(1L)));
+            StreamsTestUtils.toListAndCloseIterator(windowStore.fetch("key-one", ofEpochMilli(0L), ofEpochMilli(1L)));
         final List<KeyValue<Long, String>> keyTwoResults =
-            StreamsTestUtils.toList(windowStore.fetch("key-two", ofEpochMilli(10L), ofEpochMilli(11L)));
+            StreamsTestUtils.toListAndCloseIterator(windowStore.fetch("key-two", ofEpochMilli(10L), ofEpochMilli(11L)));
 
         assertEquals(Collections.singletonList(KeyValue.pair(0L, "value-one")), keyOneResults);
         assertEquals(Collections.singletonList(KeyValue.pair(10L, "value-two")), keyTwoResults);
@@ -150,9 +150,9 @@ public class CompositeReadOnlyWindowStoreTest {
         secondUnderlying.put("key-two", "value-two", 10L);
 
         final List<KeyValue<Long, String>> keyOneResults =
-            StreamsTestUtils.toList(windowStore.backwardFetch("key-one", ofEpochMilli(0L), ofEpochMilli(1L)));
+            StreamsTestUtils.toListAndCloseIterator(windowStore.backwardFetch("key-one", ofEpochMilli(0L), ofEpochMilli(1L)));
         final List<KeyValue<Long, String>> keyTwoResults =
-            StreamsTestUtils.toList(windowStore.backwardFetch("key-two", ofEpochMilli(10L), ofEpochMilli(11L)));
+            StreamsTestUtils.toListAndCloseIterator(windowStore.backwardFetch("key-two", ofEpochMilli(10L), ofEpochMilli(11L)));
 
         assertEquals(Collections.singletonList(KeyValue.pair(0L, "value-one")), keyOneResults);
         assertEquals(Collections.singletonList(KeyValue.pair(10L, "value-two")), keyTwoResults);
@@ -164,7 +164,7 @@ public class CompositeReadOnlyWindowStoreTest {
         underlyingWindowStore.put("some-key", "my-value", 1L);
 
         final List<KeyValue<Long, String>> results =
-            StreamsTestUtils.toList(windowStore.fetch("some-key", ofEpochMilli(0L), ofEpochMilli(2L)));
+            StreamsTestUtils.toListAndCloseIterator(windowStore.fetch("some-key", ofEpochMilli(0L), ofEpochMilli(2L)));
         assertEquals(Collections.singletonList(new KeyValue<>(1L, "my-value")), results);
     }
 
@@ -174,7 +174,7 @@ public class CompositeReadOnlyWindowStoreTest {
         underlyingWindowStore.put("some-key", "my-value", 1L);
 
         final List<KeyValue<Long, String>> results =
-            StreamsTestUtils.toList(windowStore.backwardFetch("some-key", ofEpochMilli(0L), ofEpochMilli(2L)));
+            StreamsTestUtils.toListAndCloseIterator(windowStore.backwardFetch("some-key", ofEpochMilli(0L), ofEpochMilli(2L)));
         assertEquals(Collections.singletonList(new KeyValue<>(1L, "my-value")), results);
     }
 
@@ -348,7 +348,7 @@ public class CompositeReadOnlyWindowStoreTest {
         underlyingWindowStore.put("a", "a", 0L);
         secondUnderlying.put("b", "b", 10L);
         final List<KeyValue<Windowed<String>, String>> results =
-            StreamsTestUtils.toList(windowStore.fetch("a", "b", ofEpochMilli(0), ofEpochMilli(10)));
+            StreamsTestUtils.toListAndCloseIterator(windowStore.fetch("a", "b", ofEpochMilli(0), ofEpochMilli(10)));
         assertThat(results, equalTo(Arrays.asList(
             KeyValue.pair(new Windowed<>("a", new TimeWindow(0, WINDOW_SIZE)), "a"),
             KeyValue.pair(new Windowed<>("b", new TimeWindow(10, 10 + WINDOW_SIZE)), "b"))));
@@ -362,7 +362,7 @@ public class CompositeReadOnlyWindowStoreTest {
         secondUnderlying.put("b", "b", 10L);
         secondUnderlying.put("c", "c", 10L);
         final List<KeyValue<Windowed<String>, String>> results =
-            StreamsTestUtils.toList(windowStore.fetch("b", null, ofEpochMilli(0), ofEpochMilli(10)));
+            StreamsTestUtils.toListAndCloseIterator(windowStore.fetch("b", null, ofEpochMilli(0), ofEpochMilli(10)));
         assertThat(results, equalTo(Arrays.asList(
             KeyValue.pair(new Windowed<>("b", new TimeWindow(10, 10 + WINDOW_SIZE)), "b"),
             KeyValue.pair(new Windowed<>("c", new TimeWindow(10, 10 + WINDOW_SIZE)), "c"))));
@@ -376,7 +376,7 @@ public class CompositeReadOnlyWindowStoreTest {
         secondUnderlying.put("b", "b", 10L);
         secondUnderlying.put("c", "c", 10L);
         final List<KeyValue<Windowed<String>, String>> results =
-            StreamsTestUtils.toList(windowStore.fetch(null, "b", ofEpochMilli(0), ofEpochMilli(10)));
+            StreamsTestUtils.toListAndCloseIterator(windowStore.fetch(null, "b", ofEpochMilli(0), ofEpochMilli(10)));
         assertThat(results, equalTo(Arrays.asList(
             KeyValue.pair(new Windowed<>("a", new TimeWindow(0, WINDOW_SIZE)), "a"),
             KeyValue.pair(new Windowed<>("b", new TimeWindow(10, 10 + WINDOW_SIZE)), "b"))));
@@ -390,7 +390,7 @@ public class CompositeReadOnlyWindowStoreTest {
         secondUnderlying.put("b", "b", 10L);
         secondUnderlying.put("c", "c", 10L);
         final List<KeyValue<Windowed<String>, String>> results =
-            StreamsTestUtils.toList(windowStore.fetch(null, null, ofEpochMilli(0), ofEpochMilli(10)));
+            StreamsTestUtils.toListAndCloseIterator(windowStore.fetch(null, null, ofEpochMilli(0), ofEpochMilli(10)));
         assertThat(results, equalTo(Arrays.asList(
             KeyValue.pair(new Windowed<>("a", new TimeWindow(0, WINDOW_SIZE)), "a"),
             KeyValue.pair(new Windowed<>("b", new TimeWindow(10, 10 + WINDOW_SIZE)), "b"),
@@ -405,7 +405,7 @@ public class CompositeReadOnlyWindowStoreTest {
         secondUnderlying.put("b", "b", 10L);
         secondUnderlying.put("c", "c", 10L);
         final List<KeyValue<Windowed<String>, String>> results =
-            StreamsTestUtils.toList(windowStore.backwardFetch("b", null, ofEpochMilli(0), ofEpochMilli(10)));
+            StreamsTestUtils.toListAndCloseIterator(windowStore.backwardFetch("b", null, ofEpochMilli(0), ofEpochMilli(10)));
         assertThat(results, equalTo(Arrays.asList(
             KeyValue.pair(new Windowed<>("c", new TimeWindow(10, 10 + WINDOW_SIZE)), "c"),
             KeyValue.pair(new Windowed<>("b", new TimeWindow(10, 10 + WINDOW_SIZE)), "b"))));
@@ -419,7 +419,7 @@ public class CompositeReadOnlyWindowStoreTest {
         secondUnderlying.put("b", "b", 10L);
         secondUnderlying.put("c", "c", 10L);
         final List<KeyValue<Windowed<String>, String>> results =
-            StreamsTestUtils.toList(windowStore.backwardFetch(null, "b", ofEpochMilli(0), ofEpochMilli(10)));
+            StreamsTestUtils.toListAndCloseIterator(windowStore.backwardFetch(null, "b", ofEpochMilli(0), ofEpochMilli(10)));
         assertThat(results, equalTo(Arrays.asList(
             KeyValue.pair(new Windowed<>("a", new TimeWindow(0, WINDOW_SIZE)), "a"),
             KeyValue.pair(new Windowed<>("b", new TimeWindow(10, 10 + WINDOW_SIZE)), "b")
@@ -434,7 +434,7 @@ public class CompositeReadOnlyWindowStoreTest {
         secondUnderlying.put("b", "b", 10L);
         secondUnderlying.put("c", "c", 10L);
         final List<KeyValue<Windowed<String>, String>> results =
-            StreamsTestUtils.toList(windowStore.backwardFetch(null, null, ofEpochMilli(0), ofEpochMilli(10)));
+            StreamsTestUtils.toListAndCloseIterator(windowStore.backwardFetch(null, null, ofEpochMilli(0), ofEpochMilli(10)));
         assertThat(results, equalTo(Arrays.asList(
             KeyValue.pair(new Windowed<>("a", new TimeWindow(0, WINDOW_SIZE)), "a"),
             KeyValue.pair(new Windowed<>("c", new TimeWindow(10, 10 + WINDOW_SIZE)), "c"),
@@ -448,7 +448,7 @@ public class CompositeReadOnlyWindowStoreTest {
         underlyingWindowStore.put("a", "a", 0L);
         secondUnderlying.put("b", "b", 10L);
         final List<KeyValue<Windowed<String>, String>> results =
-            StreamsTestUtils.toList(windowStore.backwardFetch("a", "b", ofEpochMilli(0), ofEpochMilli(10)));
+            StreamsTestUtils.toListAndCloseIterator(windowStore.backwardFetch("a", "b", ofEpochMilli(0), ofEpochMilli(10)));
         assertThat(results, equalTo(Arrays.asList(
             KeyValue.pair(new Windowed<>("a", new TimeWindow(0, WINDOW_SIZE)), "a"),
             KeyValue.pair(new Windowed<>("b", new TimeWindow(10, 10 + WINDOW_SIZE)), "b"))));
@@ -473,7 +473,7 @@ public class CompositeReadOnlyWindowStoreTest {
         stubProviderTwo.addStore(storeName, secondUnderlying);
         underlyingWindowStore.put("a", "a", 0L);
         secondUnderlying.put("b", "b", 10L);
-        final List<KeyValue<Windowed<String>, String>> results = StreamsTestUtils.toList(windowStore.all());
+        final List<KeyValue<Windowed<String>, String>> results = StreamsTestUtils.toListAndCloseIterator(windowStore.all());
         assertThat(results, equalTo(Arrays.asList(
             KeyValue.pair(new Windowed<>("a", new TimeWindow(0, WINDOW_SIZE)), "a"),
             KeyValue.pair(new Windowed<>("b", new TimeWindow(10, 10 + WINDOW_SIZE)), "b"))));
@@ -486,7 +486,7 @@ public class CompositeReadOnlyWindowStoreTest {
         stubProviderTwo.addStore(storeName, secondUnderlying);
         underlyingWindowStore.put("a", "a", 0L);
         secondUnderlying.put("b", "b", 10L);
-        final List<KeyValue<Windowed<String>, String>> results = StreamsTestUtils.toList(windowStore.backwardAll());
+        final List<KeyValue<Windowed<String>, String>> results = StreamsTestUtils.toListAndCloseIterator(windowStore.backwardAll());
         assertThat(results, equalTo(Arrays.asList(
             KeyValue.pair(new Windowed<>("a", new TimeWindow(0, WINDOW_SIZE)), "a"),
             KeyValue.pair(new Windowed<>("b", new TimeWindow(10, 10 + WINDOW_SIZE)), "b"))));
@@ -500,7 +500,7 @@ public class CompositeReadOnlyWindowStoreTest {
         underlyingWindowStore.put("a", "a", 0L);
         secondUnderlying.put("b", "b", 10L);
         final List<KeyValue<Windowed<String>, String>> results =
-            StreamsTestUtils.toList(windowStore.fetchAll(ofEpochMilli(0), ofEpochMilli(10)));
+            StreamsTestUtils.toListAndCloseIterator(windowStore.fetchAll(ofEpochMilli(0), ofEpochMilli(10)));
         assertThat(results, equalTo(Arrays.asList(
             KeyValue.pair(new Windowed<>("a", new TimeWindow(0, WINDOW_SIZE)), "a"),
             KeyValue.pair(new Windowed<>("b", new TimeWindow(10, 10 + WINDOW_SIZE)), "b"))));
@@ -514,7 +514,7 @@ public class CompositeReadOnlyWindowStoreTest {
         underlyingWindowStore.put("a", "a", 0L);
         secondUnderlying.put("b", "b", 10L);
         final List<KeyValue<Windowed<String>, String>> results =
-            StreamsTestUtils.toList(windowStore.backwardFetchAll(ofEpochMilli(0), ofEpochMilli(10)));
+            StreamsTestUtils.toListAndCloseIterator(windowStore.backwardFetchAll(ofEpochMilli(0), ofEpochMilli(10)));
         assertThat(results, equalTo(Arrays.asList(
             KeyValue.pair(new Windowed<>("a", new TimeWindow(0, WINDOW_SIZE)), "a"),
             KeyValue.pair(new Windowed<>("b", new TimeWindow(10, 10 + WINDOW_SIZE)), "b"))));

streams/src/test/java/org/apache/kafka/streams/state/internals/FilteredCacheIteratorTest.java

@@ -30,7 +30,7 @@ import java.util.Collections;
 import java.util.List;
 
 import static java.util.Arrays.asList;
-import static org.apache.kafka.test.StreamsTestUtils.toList;
+import static org.apache.kafka.test.StreamsTestUtils.toListAndCloseIterator;
 import static org.hamcrest.CoreMatchers.equalTo;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.junit.jupiter.api.Assertions.assertFalse;
@@ -91,7 +91,7 @@ public class FilteredCacheIteratorTest {
 
     @Test
     public void shouldAllowEntryMatchingHasNextCondition() {
-        final List<KeyValue<Bytes, LRUCacheEntry>> keyValues = toList(allIterator);
+        final List<KeyValue<Bytes, LRUCacheEntry>> keyValues = toListAndCloseIterator(allIterator);
         assertThat(keyValues, equalTo(entries));
     }
 
@@ -122,7 +122,7 @@ public class FilteredCacheIteratorTest {
 
     @Test
     public void shouldFilterEntriesNotMatchingHasNextCondition() {
-        final List<KeyValue<Bytes, LRUCacheEntry>> keyValues = toList(firstEntryIterator);
+        final List<KeyValue<Bytes, LRUCacheEntry>> keyValues = toListAndCloseIterator(firstEntryIterator);
         assertThat(keyValues, equalTo(Collections.singletonList(firstEntry)));
     }
 

streams/src/test/java/org/apache/kafka/streams/state/internals/InMemorySessionStoreTest.java

@@ -52,7 +52,11 @@ public class InMemorySessionStoreTest extends AbstractSessionBytesStoreTest {
         assertFalse(iterator.hasNext());
 
         iterator.close();
-        assertFalse(sessionStore.findSessions("a", "b", 0L, 20L).hasNext());
+
+        try (final KeyValueIterator<Windowed<String>, Long> it =
+             sessionStore.findSessions("a", "b", 0L, 20L)) {
+            assertFalse(it.hasNext());
+        }
     }
 
 }

streams/src/test/java/org/apache/kafka/streams/state/internals/ListValueStoreTest.java

@@ -40,7 +40,7 @@ import java.io.File;
 import java.util.Collections;
 
 import static java.util.Arrays.asList;
-import static org.apache.kafka.test.StreamsTestUtils.toList;
+import static org.apache.kafka.test.StreamsTestUtils.toListAndCloseIterator;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
@@ -103,7 +103,7 @@ public class ListValueStoreTest {
 
         assertEquals(
             asList(zero, zeroAgain, one, two),
-            toList(listStore.all())
+            toListAndCloseIterator(listStore.all())
         );
     }
 
@@ -130,7 +130,7 @@ public class ListValueStoreTest {
 
         assertEquals(
             asList(zero, two, four),
-            toList(listStore.all())
+            toListAndCloseIterator(listStore.all())
         );
     }
 
@@ -158,7 +158,7 @@ public class ListValueStoreTest {
 
         assertEquals(
             asList(zero, one, two1, two2, three, four),
-            toList(listStore.all())
+            toListAndCloseIterator(listStore.all())
         );
     }
 
@@ -185,7 +185,7 @@ public class ListValueStoreTest {
         it.close();
 
         // A new all() iterator after a previous all() iterator was closed should not return deleted records.
-        assertEquals(Collections.singletonList(one), toList(listStore.all()));
+        assertEquals(Collections.singletonList(one), toListAndCloseIterator(listStore.all()));
     }
 
     @ParameterizedTest

streams/src/test/java/org/apache/kafka/streams/state/internals/TimeOrderedCachingPersistentWindowStoreTest.java

@@ -72,7 +72,7 @@ import static java.util.Arrays.asList;
 import static org.apache.kafka.common.utils.Utils.mkEntry;
 import static org.apache.kafka.common.utils.Utils.mkMap;
 import static org.apache.kafka.streams.state.internals.ThreadCacheTest.memoryCacheEntrySize;
-import static org.apache.kafka.test.StreamsTestUtils.toList;
+import static org.apache.kafka.test.StreamsTestUtils.toListAndCloseIterator;
 import static org.apache.kafka.test.StreamsTestUtils.verifyAllWindowedKeyValues;
 import static org.apache.kafka.test.StreamsTestUtils.verifyKeyValueList;
 import static org.apache.kafka.test.StreamsTestUtils.verifyWindowedKeyValue;
@@ -945,7 +945,7 @@ public class TimeOrderedCachingPersistentWindowStoreTest {
                     windowedPair("a", "0001", 1),
                     windowedPair("aa", "0002", 0)
                 ),
-                toList(cachingStore.fetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
+                toListAndCloseIterator(cachingStore.fetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
                     ofEpochMilli(Long.MAX_VALUE)))
             );
         } else {
@@ -954,7 +954,7 @@ public class TimeOrderedCachingPersistentWindowStoreTest {
                     windowedPair("aa", "0002", 0),
                     windowedPair("a", "0001", 1)
                 ),
-                toList(cachingStore.fetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
+                toListAndCloseIterator(cachingStore.fetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
                     ofEpochMilli(Long.MAX_VALUE)))
             );
         }
@@ -976,7 +976,7 @@ public class TimeOrderedCachingPersistentWindowStoreTest {
             KeyValue.pair(SEGMENT_INTERVAL, bytesValue("0005"))
         );
         final List<KeyValue<Long, byte[]>> actual =
-            toList(cachingStore.fetch(bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)));
+            toListAndCloseIterator(cachingStore.fetch(bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)));
         verifyKeyValueList(expected, actual);
     }
 
@@ -996,7 +996,7 @@ public class TimeOrderedCachingPersistentWindowStoreTest {
             KeyValue.pair(0L, bytesValue("0001"))
         );
         final List<KeyValue<Long, byte[]>> actual =
-            toList(cachingStore.backwardFetch(bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)));
+            toListAndCloseIterator(cachingStore.backwardFetch(bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)));
         verifyKeyValueList(expected, actual);
     }
 
@@ -1016,14 +1016,14 @@ public class TimeOrderedCachingPersistentWindowStoreTest {
                 windowedPair("a", "0003", 1),
                 windowedPair("a", "0005", SEGMENT_INTERVAL)
             ),
-            toList(cachingStore.fetch(bytesKey("a"), bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
+            toListAndCloseIterator(cachingStore.fetch(bytesKey("a"), bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
         );
 
         verifyKeyValueList(
             asList(
                 windowedPair("aa", "0002", 0),
                 windowedPair("aa", "0004", 1)),
-            toList(cachingStore.fetch(bytesKey("aa"), bytesKey("aa"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
+            toListAndCloseIterator(cachingStore.fetch(bytesKey("aa"), bytesKey("aa"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
         );
 
         if (hasIndex) {
@@ -1035,7 +1035,7 @@ public class TimeOrderedCachingPersistentWindowStoreTest {
                     windowedPair("aa", "0004", 1),
                     windowedPair("a", "0005", SEGMENT_INTERVAL)
                 ),
-                toList(cachingStore.fetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
+                toListAndCloseIterator(cachingStore.fetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
                     ofEpochMilli(Long.MAX_VALUE)))
             );
         } else {
@@ -1047,7 +1047,7 @@ public class TimeOrderedCachingPersistentWindowStoreTest {
                     windowedPair("aa", "0004", 1),
                     windowedPair("a", "0005", SEGMENT_INTERVAL)
                 ),
-                toList(cachingStore.fetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
+                toListAndCloseIterator(cachingStore.fetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
                     ofEpochMilli(Long.MAX_VALUE)))
             );
         }
@@ -1069,14 +1069,14 @@ public class TimeOrderedCachingPersistentWindowStoreTest {
                 windowedPair("a", "0003", 1),
                 windowedPair("a", "0001", 0)
             ),
-            toList(cachingStore.backwardFetch(bytesKey("a"), bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
+            toListAndCloseIterator(cachingStore.backwardFetch(bytesKey("a"), bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
         );
 
         verifyKeyValueList(
             asList(
                 windowedPair("aa", "0004", 1),
                 windowedPair("aa", "0002", 0)),
-            toList(cachingStore.backwardFetch(bytesKey("aa"), bytesKey("aa"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
+            toListAndCloseIterator(cachingStore.backwardFetch(bytesKey("aa"), bytesKey("aa"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
         );
 
         if (!hasIndex) {
@@ -1089,7 +1089,7 @@ public class TimeOrderedCachingPersistentWindowStoreTest {
                     windowedPair("aa", "0002", 0),
                     windowedPair("a", "0001", 0)
                 ),
-                toList(cachingStore.backwardFetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
+                toListAndCloseIterator(cachingStore.backwardFetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
                     ofEpochMilli(Long.MAX_VALUE)))
             );
         } else {
@@ -1102,7 +1102,7 @@ public class TimeOrderedCachingPersistentWindowStoreTest {
                     windowedPair("a", "0003", 1),
                     windowedPair("a", "0001", 0)
                 ),
-                toList(cachingStore.backwardFetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
+                toListAndCloseIterator(cachingStore.backwardFetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
                     ofEpochMilli(Long.MAX_VALUE)))
             );
         }

streams/src/test/java/org/apache/kafka/streams/state/internals/TimeOrderedWindowStoreTest.java

@@ -71,7 +71,7 @@ import static java.util.Arrays.asList;
 import static org.apache.kafka.common.utils.Utils.mkEntry;
 import static org.apache.kafka.common.utils.Utils.mkMap;
 import static org.apache.kafka.streams.state.internals.ThreadCacheTest.memoryCacheEntrySize;
-import static org.apache.kafka.test.StreamsTestUtils.toList;
+import static org.apache.kafka.test.StreamsTestUtils.toListAndCloseIterator;
 import static org.apache.kafka.test.StreamsTestUtils.verifyAllWindowedKeyValues;
 import static org.apache.kafka.test.StreamsTestUtils.verifyKeyValueList;
 import static org.apache.kafka.test.StreamsTestUtils.verifyWindowedKeyValue;
@@ -951,7 +951,7 @@ public class TimeOrderedWindowStoreTest {
                     windowedPair("a", "0001", 1),
                     windowedPair("aa", "0002", 0)
                 ),
-                toList(cachingStore.fetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
+                toListAndCloseIterator(cachingStore.fetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
                     ofEpochMilli(Long.MAX_VALUE)))
             );
         } else {
@@ -960,7 +960,7 @@ public class TimeOrderedWindowStoreTest {
                     windowedPair("aa", "0002", 0),
                     windowedPair("a", "0001", 1)
                 ),
-                toList(cachingStore.fetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
+                toListAndCloseIterator(cachingStore.fetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
                     ofEpochMilli(Long.MAX_VALUE)))
             );
         }
@@ -982,7 +982,7 @@ public class TimeOrderedWindowStoreTest {
             KeyValue.pair(SEGMENT_INTERVAL, bytesValue("0005"))
         );
         final List<KeyValue<Long, byte[]>> actual =
-            toList(cachingStore.fetch(bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)));
+            toListAndCloseIterator(cachingStore.fetch(bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)));
         verifyKeyValueList(expected, actual);
     }
 
@@ -1002,7 +1002,7 @@ public class TimeOrderedWindowStoreTest {
             KeyValue.pair(0L, bytesValue("0001"))
         );
         final List<KeyValue<Long, byte[]>> actual =
-            toList(cachingStore.backwardFetch(bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)));
+            toListAndCloseIterator(cachingStore.backwardFetch(bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)));
         verifyKeyValueList(expected, actual);
     }
 
@@ -1022,14 +1022,14 @@ public class TimeOrderedWindowStoreTest {
                 windowedPair("a", "0003", 1),
                 windowedPair("a", "0005", SEGMENT_INTERVAL)
             ),
-            toList(cachingStore.fetch(bytesKey("a"), bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
+            toListAndCloseIterator(cachingStore.fetch(bytesKey("a"), bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
         );
 
         verifyKeyValueList(
             asList(
                 windowedPair("aa", "0002", 0),
                 windowedPair("aa", "0004", 1)),
-            toList(cachingStore.fetch(bytesKey("aa"), bytesKey("aa"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
+            toListAndCloseIterator(cachingStore.fetch(bytesKey("aa"), bytesKey("aa"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
         );
 
         if (hasIndex) {
@@ -1041,7 +1041,7 @@ public class TimeOrderedWindowStoreTest {
                     windowedPair("aa", "0004", 1),
                     windowedPair("a", "0005", SEGMENT_INTERVAL)
                 ),
-                toList(cachingStore.fetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
+                toListAndCloseIterator(cachingStore.fetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
                     ofEpochMilli(Long.MAX_VALUE)))
             );
         } else {
@@ -1053,7 +1053,7 @@ public class TimeOrderedWindowStoreTest {
                     windowedPair("aa", "0004", 1),
                     windowedPair("a", "0005", SEGMENT_INTERVAL)
                 ),
-                toList(cachingStore.fetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
+                toListAndCloseIterator(cachingStore.fetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
                     ofEpochMilli(Long.MAX_VALUE)))
             );
         }
@@ -1075,14 +1075,14 @@ public class TimeOrderedWindowStoreTest {
                 windowedPair("a", "0003", 1),
                 windowedPair("a", "0001", 0)
             ),
-            toList(cachingStore.backwardFetch(bytesKey("a"), bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
+            toListAndCloseIterator(cachingStore.backwardFetch(bytesKey("a"), bytesKey("a"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
         );
 
         verifyKeyValueList(
             asList(
                 windowedPair("aa", "0004", 1),
                 windowedPair("aa", "0002", 0)),
-            toList(cachingStore.backwardFetch(bytesKey("aa"), bytesKey("aa"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
+            toListAndCloseIterator(cachingStore.backwardFetch(bytesKey("aa"), bytesKey("aa"), ofEpochMilli(0), ofEpochMilli(Long.MAX_VALUE)))
         );
 
         if (!hasIndex) {
@@ -1095,7 +1095,7 @@ public class TimeOrderedWindowStoreTest {
                     windowedPair("aa", "0002", 0),
                     windowedPair("a", "0001", 0)
                 ),
-                toList(cachingStore.backwardFetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
+                toListAndCloseIterator(cachingStore.backwardFetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
                     ofEpochMilli(Long.MAX_VALUE)))
             );
         } else {
@@ -1108,7 +1108,7 @@ public class TimeOrderedWindowStoreTest {
                     windowedPair("a", "0003", 1),
                     windowedPair("a", "0001", 0)
                 ),
-                toList(cachingStore.backwardFetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
+                toListAndCloseIterator(cachingStore.backwardFetch(bytesKey("a"), bytesKey("aa"), ofEpochMilli(0),
                     ofEpochMilli(Long.MAX_VALUE)))
             );
         }

streams/src/test/java/org/apache/kafka/streams/state/internals/WindowKeySchemaTest.java

@@ -126,7 +126,7 @@ public class WindowKeySchemaTest {
     private final Window window = new TimeWindow(startTime, endTime);
     private final Windowed<String> windowedKey = new Windowed<>(key, window);
     private KeySchema keySchema;
-    private final Serde<Windowed<String>> keySerde = new WindowedSerdes.TimeWindowedSerde<>(serde, Long.MAX_VALUE);
+    private final Serde<Windowed<String>> keySerde = new WindowedSerdes.TimeWindowedSerde<>(serde, endTime - startTime);
     private final StateSerdes<String, byte[]> stateSerdes = new StateSerdes<>("dummy", serde, Serdes.ByteArray());
     public SchemaType schemaType;
 
@@ -401,7 +401,7 @@ public class WindowKeySchemaTest {
         final byte[] bytes = keySerde.serializer().serialize(topic, windowedKey);
         final Windowed<String> result = keySerde.deserializer().deserialize(topic, bytes);
         // TODO: fix this part as last bits of KAFKA-4468
-        assertEquals(new Windowed<>(key, new TimeWindow(startTime, Long.MAX_VALUE)), result);
+        assertEquals(new Windowed<>(key, new TimeWindow(startTime, endTime)), result);
     }
 
     @EnumSource(SchemaType.class)

streams/src/test/java/org/apache/kafka/test/StreamsTestUtils.java

@@ -35,8 +35,6 @@ import org.apache.kafka.streams.state.KeyValueIterator;
 
 import org.mockito.quality.Strictness;
 
-import java.io.Closeable;
-import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -116,20 +114,16 @@ public final class StreamsTestUtils {
         return getStreamsConfig(UUID.randomUUID().toString());
     }
 
-    public static <K, V> List<KeyValue<K, V>> toList(final Iterator<KeyValue<K, V>> iterator) {
+    public static <K, V> List<KeyValue<K, V>> toListAndCloseIterator(final KeyValueIterator<K, V> iterator) {
-        final List<KeyValue<K, V>> results = new ArrayList<>();
+        try (iterator) {
+            final List<KeyValue<K, V>> results = new ArrayList<>();
 
-        while (iterator.hasNext()) {
+            while (iterator.hasNext()) {
-            results.add(iterator.next());
+                results.add(iterator.next());
+            }
+
+            return results;
         }
-
-        if (iterator instanceof Closeable) {
-            try {
-                ((Closeable) iterator).close();
-            } catch (IOException e) { /* do nothing */ }
-        }
-
-        return results;
     }
 
     public static <K, V> Set<KeyValue<K, V>> toSet(final Iterator<KeyValue<K, V>> iterator) {
@@ -141,7 +135,7 @@ public final class StreamsTestUtils {
         return results;
     }
 
-    public static <K, V> Set<V> valuesToSet(final Iterator<KeyValue<K, V>> iterator) {
+    public static <K, V> Set<V> valuesToSet(final KeyValueIterator<K, V> iterator) {
         final Set<V> results = new HashSet<>();
 
         while (iterator.hasNext()) {
@@ -150,6 +144,12 @@ public final class StreamsTestUtils {
         return results;
     }
 
+    public static <K, V> Set<V> valuesToSetAndCloseIterator(final KeyValueIterator<K, V> iterator) {
+        try (iterator) {
+            return valuesToSet(iterator);
+        }
+    }
+
     public static <K> void verifyKeyValueList(final List<KeyValue<K, byte[]>> expected, final List<KeyValue<K, byte[]>> actual) {
         assertThat(actual.size(), equalTo(expected.size()));
         for (int i = 0; i < actual.size(); i++) {
@@ -254,8 +254,8 @@ public final class StreamsTestUtils {
     }
 
     /**
-     * Used to keep tests simple, and ignore calls from {@link org.apache.kafka.streams.internals.ApiUtils#checkSupplier(Supplier)} )}.
+     * Used to keep tests simple, and ignore calls from {@link org.apache.kafka.streams.internals.ApiUtils#checkSupplier(Supplier)}.
-     * @return true if the stack context is within a {@link org.apache.kafka.streams.internals.ApiUtils#checkSupplier(Supplier)} )} call
+     * @return true if the stack context is within a {@link org.apache.kafka.streams.internals.ApiUtils#checkSupplier(Supplier)} call
      */
     public static boolean isCheckSupplierCall() {
         return Arrays.stream(Thread.currentThread().getStackTrace())