Enable unchecked compilation warnings

See gh-21271

buildSrc/src/main/java/org/springframework/boot/build/JavaConventions.java

@@ -157,7 +157,7 @@ class JavaConventions {
 				args.add("-parameters");
 			}
 			if (JavaVersion.current() == JavaVersion.VERSION_1_8) {
-				args.add("-Werror");
+				args.addAll(Arrays.asList("-Werror", "-Xlint:unchecked"));
 			}
 		});
 	}

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/trace/http/reactive/HttpTraceWebFilterTests.java

@@ -89,9 +89,10 @@ class HttpTraceWebFilterTests {
 		executeFilter(new ServerWebExchangeDecorator(
 				MockServerWebExchange.from(MockServerHttpRequest.get("https://api.example.com"))) {
 
+			@SuppressWarnings("unchecked")
 			@Override
-			public Mono<Principal> getPrincipal() {
-				return Mono.just(principal);
+			public <T extends Principal> Mono<T> getPrincipal() {
+				return Mono.just((T) principal);
 			}
 
 		}, (exchange) -> {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/cache/CacheAutoConfigurationTests.java

@@ -42,6 +42,7 @@ import org.springframework.beans.factory.BeanCreationException;
 import org.springframework.beans.factory.config.BeanPostProcessor;
 import org.springframework.boot.autoconfigure.AutoConfigurations;
 import org.springframework.boot.autoconfigure.cache.support.MockCachingProvider;
+import org.springframework.boot.autoconfigure.cache.support.MockCachingProvider.MockCacheManager;
 import org.springframework.boot.autoconfigure.hazelcast.HazelcastAutoConfiguration;
 import org.springframework.boot.test.context.assertj.AssertableApplicationContext;
 import org.springframework.boot.testsupport.classpath.ClassPathExclusions;
@@ -354,8 +355,9 @@ class CacheAutoConfigurationTests extends AbstractCacheAutoConfigurationTests {
 					assertThat(cacheManager.getCacheNames()).containsOnly("one", "two");
 					CompleteConfiguration<?, ?> defaultCacheConfiguration = context
 							.getBean(CompleteConfiguration.class);
-					verify(cacheManager.getCacheManager()).createCache("one", defaultCacheConfiguration);
-					verify(cacheManager.getCacheManager()).createCache("two", defaultCacheConfiguration);
+					MockCacheManager mockCacheManager = (MockCacheManager) cacheManager.getCacheManager();
+					assertThat(mockCacheManager.getConfigurations()).containsEntry("one", defaultCacheConfiguration)
+							.containsEntry("two", defaultCacheConfiguration);
 				});
 	}
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/cache/support/MockCachingProvider.java

@@ -27,8 +27,6 @@ import javax.cache.configuration.Configuration;
 import javax.cache.configuration.OptionalFeature;
 import javax.cache.spi.CachingProvider;
 
-import static org.mockito.ArgumentMatchers.any;
-import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.BDDMockito.given;
 import static org.mockito.Mockito.mock;
 
@@ -41,25 +39,8 @@ import static org.mockito.Mockito.mock;
 public class MockCachingProvider implements CachingProvider {
 
 	@Override
-	@SuppressWarnings("rawtypes")
 	public CacheManager getCacheManager(URI uri, ClassLoader classLoader, Properties properties) {
-		CacheManager cacheManager = mock(CacheManager.class);
-		given(cacheManager.getURI()).willReturn(uri);
-		given(cacheManager.getClassLoader()).willReturn(classLoader);
-		final Map<String, Cache> caches = new HashMap<>();
-		given(cacheManager.getCacheNames()).willReturn(caches.keySet());
-		given(cacheManager.getCache(anyString())).willAnswer((invocation) -> {
-			String cacheName = invocation.getArgument(0);
-			return caches.get(cacheName);
-		});
-		given(cacheManager.createCache(anyString(), any(Configuration.class))).will((invocation) -> {
-			String cacheName = invocation.getArgument(0);
-			Cache cache = mock(Cache.class);
-			given(cache.getName()).willReturn(cacheName);
-			caches.put(cacheName, cache);
-			return cache;
-		});
-		return cacheManager;
+		return new MockCacheManager(uri, classLoader, properties);
 	}
 
 	@Override
@@ -104,4 +85,108 @@ public class MockCachingProvider implements CachingProvider {
 		return false;
 	}
 
+	public static class MockCacheManager implements CacheManager {
+
+		private final Map<String, Configuration<?, ?>> configurations = new HashMap<>();
+
+		private final Map<String, Cache<?, ?>> caches = new HashMap<>();
+
+		private final URI uri;
+
+		private final ClassLoader classLoader;
+
+		private final Properties properties;
+
+		private boolean closed;
+
+		public MockCacheManager(URI uri, ClassLoader classLoader, Properties properties) {
+			this.uri = uri;
+			this.classLoader = classLoader;
+			this.properties = properties;
+		}
+
+		@Override
+		public CachingProvider getCachingProvider() {
+			throw new UnsupportedOperationException();
+		}
+
+		@Override
+		public URI getURI() {
+			return this.uri;
+		}
+
+		@Override
+		public ClassLoader getClassLoader() {
+			return this.classLoader;
+		}
+
+		@Override
+		public Properties getProperties() {
+			return this.properties;
+		}
+
+		@Override
+		@SuppressWarnings("unchecked")
+		public <K, V, C extends Configuration<K, V>> Cache<K, V> createCache(String cacheName, C configuration)
+				throws IllegalArgumentException {
+			this.configurations.put(cacheName, configuration);
+			Cache<K, V> cache = mock(Cache.class);
+			given(cache.getName()).willReturn(cacheName);
+			this.caches.put(cacheName, cache);
+			return cache;
+		}
+
+		@Override
+		@SuppressWarnings("unchecked")
+		public <K, V> Cache<K, V> getCache(String cacheName, Class<K> keyType, Class<V> valueType) {
+			return (Cache<K, V>) this.caches.get(cacheName);
+		}
+
+		@Override
+		@SuppressWarnings("unchecked")
+		public <K, V> Cache<K, V> getCache(String cacheName) {
+			return (Cache<K, V>) this.caches.get(cacheName);
+		}
+
+		@Override
+		public Iterable<String> getCacheNames() {
+			return this.caches.keySet();
+		}
+
+		@Override
+		public void destroyCache(String cacheName) {
+			this.caches.remove(cacheName);
+		}
+
+		@Override
+		public void enableManagement(String cacheName, boolean enabled) {
+			throw new UnsupportedOperationException();
+		}
+
+		@Override
+		public void enableStatistics(String cacheName, boolean enabled) {
+			throw new UnsupportedOperationException();
+		}
+
+		@Override
+		public void close() {
+			this.closed = true;
+		}
+
+		@Override
+		public boolean isClosed() {
+			return this.closed;
+		}
+
+		@Override
+		public <T> T unwrap(Class<T> clazz) {
+			throw new UnsupportedOperationException();
+		}
+
+		public Map<String, Configuration<?, ?>> getConfigurations() {
+			return this.configurations;
+		}
+
+	}
+
 }

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/DependencyFilter.java

@@ -46,11 +46,10 @@ public abstract class DependencyFilter extends AbstractArtifactsFilter {
 	}
 
 	@Override
-	@SuppressWarnings({ "rawtypes", "unchecked" })
-	public Set filter(Set artifacts) throws ArtifactFilterException {
-		Set result = new HashSet();
-		for (Object artifact : artifacts) {
-			if (!filter((Artifact) artifact)) {
+	public Set<Artifact> filter(Set<Artifact> artifacts) throws ArtifactFilterException {
+		Set<Artifact> result = new HashSet<>();
+		for (Artifact artifact : artifacts) {
+			if (!filter(artifact)) {
 				result.add(artifact);
 			}
 		}