KAFKA-3009; Disallow star imports

Summary of code changes
------------------------------------
1) Added a new Checkstyle rule to flag any code using star imports
2) Fixed ALL existing code violations using star imports

Testing
-----------
Local build was successful
ALL JUnits ran successfully on local.

ewencp - Request you to please review changes. Thank you !

I state that the contribution is my original work and I license the work to the project under the project's open source license.

Author: manasvigupta <manasvigupta@yahoo.co.in>

Reviewers: Ewen Cheslack-Postava <ewen@confluent.io>

Closes #700 from manasvigupta/KAFKA-3009

checkstyle/checkstyle.xml

@@ -64,6 +64,7 @@
     <module name="ParameterName"/>
     <module name="StaticVariableName"/>
     <module name="TypeName"/>
+    <module name="AvoidStarImport"/>
 
     <!-- dependencies -->
     <module name="ImportControl">

clients/src/main/java/org/apache/kafka/clients/producer/KafkaProducer.java

@@ -13,7 +13,11 @@
 package org.apache.kafka.clients.producer;
 
 import java.net.InetSocketAddress;
-import java.util.*;
+import java.util.Collections;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Properties;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;

clients/src/main/java/org/apache/kafka/clients/producer/MockProducer.java

@@ -29,7 +29,11 @@ import java.util.concurrent.TimeUnit;
 import org.apache.kafka.clients.producer.internals.FutureRecordMetadata;
 import org.apache.kafka.clients.producer.internals.DefaultPartitioner;
 import org.apache.kafka.clients.producer.internals.ProduceRequestResult;
-import org.apache.kafka.common.*;
+import org.apache.kafka.common.Cluster;
+import org.apache.kafka.common.Metric;
+import org.apache.kafka.common.MetricName;
+import org.apache.kafka.common.PartitionInfo;
+import org.apache.kafka.common.TopicPartition;
 import org.apache.kafka.common.serialization.Serializer;
 
 

clients/src/main/java/org/apache/kafka/common/Cluster.java

@@ -15,7 +15,13 @@ package org.apache.kafka.common;
 import org.apache.kafka.common.utils.Utils;
 
 import java.net.InetSocketAddress;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
 
 /**
  * A representation of a subset of the nodes, topics, and partitions in the Kafka cluster.

clients/src/main/java/org/apache/kafka/common/config/AbstractConfig.java

@@ -12,7 +12,13 @@
  */
 package org.apache.kafka.common.config;
 
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
 
 import org.apache.kafka.common.Configurable;
 import org.apache.kafka.common.KafkaException;

clients/src/main/java/org/apache/kafka/common/network/Selector.java

@@ -15,8 +15,20 @@ package org.apache.kafka.common.network;
 import java.io.IOException;
 import java.net.InetSocketAddress;
 import java.net.Socket;
-import java.nio.channels.*;
-import java.util.*;
+import java.nio.channels.CancelledKeyException;
+import java.nio.channels.ClosedChannelException;
+import java.nio.channels.SelectionKey;
+import java.nio.channels.SocketChannel;
+import java.nio.channels.UnresolvedAddressException;
+import java.util.ArrayDeque;
+import java.util.ArrayList;
+import java.util.Deque;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
 import java.util.concurrent.TimeUnit;
 
 import org.apache.kafka.common.KafkaException;

clients/src/main/java/org/apache/kafka/common/protocol/Errors.java

@@ -19,8 +19,30 @@ package org.apache.kafka.common.protocol;
 import java.util.HashMap;
 import java.util.Map;
 
-import org.apache.kafka.common.errors.*;
+import org.apache.kafka.common.errors.ApiException;
+import org.apache.kafka.common.errors.AuthorizationException;
+import org.apache.kafka.common.errors.BrokerNotAvailableException;
 import org.apache.kafka.common.errors.ControllerMovedException;
+import org.apache.kafka.common.errors.CorruptRecordException;
+import org.apache.kafka.common.errors.GroupCoordinatorNotAvailableException;
+import org.apache.kafka.common.errors.GroupLoadInProgressException;
+import org.apache.kafka.common.errors.IllegalGenerationException;
+import org.apache.kafka.common.errors.InvalidRequiredAcksException;
+import org.apache.kafka.common.errors.InvalidTopicException;
+import org.apache.kafka.common.errors.LeaderNotAvailableException;
+import org.apache.kafka.common.errors.NetworkException;
+import org.apache.kafka.common.errors.NotCoordinatorForGroupException;
+import org.apache.kafka.common.errors.NotEnoughReplicasAfterAppendException;
+import org.apache.kafka.common.errors.NotEnoughReplicasException;
+import org.apache.kafka.common.errors.NotLeaderForPartitionException;
+import org.apache.kafka.common.errors.OffsetMetadataTooLarge;
+import org.apache.kafka.common.errors.RebalanceInProgressException;
+import org.apache.kafka.common.errors.RecordBatchTooLargeException;
+import org.apache.kafka.common.errors.RecordTooLargeException;
+import org.apache.kafka.common.errors.TimeoutException;
+import org.apache.kafka.common.errors.UnknownMemberIdException;
+import org.apache.kafka.common.errors.UnknownServerException;
+import org.apache.kafka.common.errors.UnknownTopicOrPartitionException;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 

clients/src/main/java/org/apache/kafka/common/requests/ControlledShutdownResponse.java

@@ -19,7 +19,10 @@ import org.apache.kafka.common.protocol.types.Schema;
 import org.apache.kafka.common.protocol.types.Struct;
 
 import java.nio.ByteBuffer;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
 
 public class ControlledShutdownResponse extends AbstractRequestResponse {
 

clients/src/main/java/org/apache/kafka/common/requests/LeaderAndIsrRequest.java

@@ -25,7 +25,12 @@ import org.apache.kafka.common.protocol.types.Schema;
 import org.apache.kafka.common.protocol.types.Struct;
 
 import java.nio.ByteBuffer;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
 
 public class LeaderAndIsrRequest extends AbstractRequest {
 

clients/src/main/java/org/apache/kafka/common/requests/StopReplicaRequest.java

@@ -21,7 +21,12 @@ import org.apache.kafka.common.protocol.types.Schema;
 import org.apache.kafka.common.protocol.types.Struct;
 
 import java.nio.ByteBuffer;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
 
 public class StopReplicaRequest extends AbstractRequest {
     private static final Schema CURRENT_SCHEMA = ProtoUtils.currentRequestSchema(ApiKeys.STOP_REPLICA.id);

clients/src/main/java/org/apache/kafka/common/requests/StopReplicaResponse.java

@@ -21,7 +21,10 @@ import org.apache.kafka.common.protocol.types.Schema;
 import org.apache.kafka.common.protocol.types.Struct;
 
 import java.nio.ByteBuffer;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
 
 public class StopReplicaResponse extends AbstractRequestResponse {
     private static final Schema CURRENT_SCHEMA = ProtoUtils.currentResponseSchema(ApiKeys.STOP_REPLICA.id);

clients/src/main/java/org/apache/kafka/common/requests/UpdateMetadataRequest.java

@@ -22,7 +22,13 @@ import org.apache.kafka.common.protocol.types.Schema;
 import org.apache.kafka.common.protocol.types.Struct;
 
 import java.nio.ByteBuffer;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
 
 public class UpdateMetadataRequest extends AbstractRequest {
 

clients/src/main/java/org/apache/kafka/common/security/ssl/SslFactory.java

@@ -22,15 +22,20 @@ import org.apache.kafka.common.config.SslConfigs;
 import org.apache.kafka.common.network.Mode;
 import org.apache.kafka.common.config.types.Password;
 
-import javax.net.ssl.*;
 import java.io.FileInputStream;
 import java.io.IOException;
 import java.security.GeneralSecurityException;
 import java.security.KeyStore;
-
 import java.util.List;
 import java.util.Map;
 
+import javax.net.ssl.KeyManager;
+import javax.net.ssl.KeyManagerFactory;
+import javax.net.ssl.SSLContext;
+import javax.net.ssl.SSLEngine;
+import javax.net.ssl.SSLParameters;
+import javax.net.ssl.TrustManagerFactory;
+
 public class SslFactory implements Configurable {
 
     private String protocol;

clients/src/test/java/org/apache/kafka/clients/MetadataTest.java

@@ -27,7 +27,12 @@ import org.apache.kafka.test.TestUtils;
 import org.junit.After;
 import org.junit.Test;
 
-import static org.junit.Assert.*;
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
 
 public class MetadataTest {
 

clients/src/test/java/org/apache/kafka/clients/producer/internals/BufferPoolTest.java

@@ -29,7 +29,9 @@ import java.util.List;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.atomic.AtomicBoolean;
 
-import static org.junit.Assert.*;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+import static org.junit.Assert.assertEquals;
 
 public class BufferPoolTest {
     private MockTime time = new MockTime();

clients/src/test/java/org/apache/kafka/common/network/SelectorTest.java

@@ -21,7 +21,6 @@ import java.io.IOException;
 import java.net.InetSocketAddress;
 import java.net.ServerSocket;
 import java.nio.ByteBuffer;
-import java.util.*;
 
 import org.apache.kafka.common.metrics.Metrics;
 import org.apache.kafka.common.utils.MockTime;

clients/src/test/java/org/apache/kafka/common/record/MemoryRecordsTest.java

@@ -22,7 +22,11 @@ import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
 import java.nio.ByteBuffer;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.List;
 
 import org.junit.Test;
 import org.junit.runner.RunWith;

clients/src/test/java/org/apache/kafka/common/security/ssl/SslFactoryTest.java

@@ -12,15 +12,15 @@
  */
 package org.apache.kafka.common.security.ssl;
 
-import javax.net.ssl.*;
-
 import java.io.File;
 import java.util.Map;
 
+import javax.net.ssl.SSLEngine;
+
 import org.apache.kafka.test.TestSslUtils;
 import org.apache.kafka.common.network.Mode;
-
 import org.junit.Test;
+
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertArrayEquals;

clients/src/test/java/org/apache/kafka/common/utils/AbstractIteratorTest.java

@@ -20,7 +20,11 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+import java.util.NoSuchElementException;
 
 import org.junit.Test;
 

clients/src/test/java/org/apache/kafka/common/utils/UtilsTest.java

@@ -25,7 +25,7 @@ import org.junit.Test;
 import static org.apache.kafka.common.utils.Utils.getHost;
 import static org.apache.kafka.common.utils.Utils.getPort;
 import static org.apache.kafka.common.utils.Utils.formatAddress;
-import static org.junit.Assert.*;
+import static org.junit.Assert.assertEquals;
 
 public class UtilsTest {
 

clients/src/test/java/org/apache/kafka/test/TestSslUtils.java

@@ -27,8 +27,17 @@ import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.EOFException;
 import java.math.BigInteger;
+
 import javax.net.ssl.TrustManagerFactory;
-import java.security.*;
+
+import java.security.GeneralSecurityException;
+import java.security.Key;
+import java.security.KeyPair;
+import java.security.KeyPairGenerator;
+import java.security.KeyStore;
+import java.security.NoSuchAlgorithmException;
+import java.security.SecureRandom;
+import java.security.Security;
 import java.security.cert.Certificate;
 import java.security.cert.CertificateException;
 import java.security.cert.X509Certificate;

connect/api/src/main/java/org/apache/kafka/connect/data/ConnectSchema.java

@@ -21,7 +21,11 @@ import org.apache.kafka.connect.errors.DataException;
 
 import java.math.BigDecimal;
 import java.nio.ByteBuffer;
-import java.util.*;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
 
 public class ConnectSchema implements Schema {
     /**

connect/file/src/main/java/org/apache/kafka/connect/file/FileStreamSourceTask.java

@@ -17,6 +17,17 @@
 
 package org.apache.kafka.connect.file;
 
+import java.io.BufferedReader;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+
 import org.apache.kafka.connect.data.Schema;
 import org.apache.kafka.connect.errors.ConnectException;
 import org.apache.kafka.connect.source.SourceRecord;
@@ -24,9 +35,6 @@ import org.apache.kafka.connect.source.SourceTask;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.io.*;
-import java.util.*;
-
 /**
  * FileStreamSourceTask reads from stdin or a file.
  */

connect/json/src/main/java/org/apache/kafka/connect/json/JsonConverter.java

@@ -25,7 +25,16 @@ import org.apache.kafka.common.cache.Cache;
 import org.apache.kafka.common.cache.LRUCache;
 import org.apache.kafka.common.cache.SynchronizedCache;
 import org.apache.kafka.common.errors.SerializationException;
-import org.apache.kafka.connect.data.*;
+import org.apache.kafka.connect.data.SchemaBuilder;
+import org.apache.kafka.connect.data.Schema;
+import org.apache.kafka.connect.data.Struct;
+import org.apache.kafka.connect.data.Field;
+import org.apache.kafka.connect.data.ConnectSchema;
+import org.apache.kafka.connect.data.SchemaAndValue;
+import org.apache.kafka.connect.data.Timestamp;
+import org.apache.kafka.connect.data.Time;
+import org.apache.kafka.connect.data.Decimal;
+import org.apache.kafka.connect.data.Date;
 import org.apache.kafka.connect.errors.DataException;
 import org.apache.kafka.connect.storage.Converter;
 

connect/runtime/src/main/java/org/apache/kafka/connect/runtime/Worker.java

@@ -29,7 +29,11 @@ import org.apache.kafka.connect.connector.Task;
 import org.apache.kafka.connect.errors.ConnectException;
 import org.apache.kafka.connect.sink.SinkTask;
 import org.apache.kafka.connect.source.SourceTask;
-import org.apache.kafka.connect.storage.*;
+import org.apache.kafka.connect.storage.Converter;
+import org.apache.kafka.connect.storage.OffsetBackingStore;
+import org.apache.kafka.connect.storage.OffsetStorageReader;
+import org.apache.kafka.connect.storage.OffsetStorageWriter;
+import org.apache.kafka.connect.storage.OffsetStorageReaderImpl;
 import org.apache.kafka.connect.util.ConnectorTaskId;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;

connect/runtime/src/main/java/org/apache/kafka/connect/storage/FileOffsetBackingStore.java

@@ -21,7 +21,14 @@ import org.apache.kafka.connect.errors.ConnectException;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.io.*;
+import java.io.EOFException;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
 import java.nio.ByteBuffer;
 import java.util.HashMap;
 import java.util.Map;

connect/runtime/src/main/java/org/apache/kafka/connect/storage/OffsetStorageWriter.java

@@ -23,7 +23,9 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.nio.ByteBuffer;
-import java.util.*;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Map;
 import java.util.concurrent.Future;
 
 /**

connect/runtime/src/test/java/org/apache/kafka/connect/runtime/WorkerSourceTaskTest.java

@@ -45,13 +45,21 @@ import org.powermock.api.easymock.annotation.Mock;
 import org.powermock.modules.junit4.PowerMockRunner;
 import org.powermock.reflect.Whitebox;
 
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 
-import static org.junit.Assert.*;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.assertNull;
 
 @RunWith(PowerMockRunner.class)
 public class WorkerSourceTaskTest extends ThreadedTest {

connect/runtime/src/test/java/org/apache/kafka/connect/storage/OffsetStorageWriterTest.java

@@ -35,7 +35,12 @@ import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
-import java.util.concurrent.*;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.Callable;
 
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;

tools/src/main/java/org/apache/kafka/tools/ProducerPerformance.java

@@ -18,13 +18,17 @@ import java.util.Arrays;
 import java.util.List;
 import java.util.Properties;
 
+import org.apache.kafka.clients.producer.Callback;
+import org.apache.kafka.clients.producer.KafkaProducer;
+import org.apache.kafka.clients.producer.ProducerConfig;
+import org.apache.kafka.clients.producer.ProducerRecord;
+import org.apache.kafka.clients.producer.RecordMetadata;
+
 import net.sourceforge.argparse4j.ArgumentParsers;
 import net.sourceforge.argparse4j.inf.ArgumentParser;
 import net.sourceforge.argparse4j.inf.ArgumentParserException;
 import net.sourceforge.argparse4j.inf.Namespace;
 
-import org.apache.kafka.clients.producer.*;
-
 public class ProducerPerformance {
 
     public static void main(String[] args) throws Exception {