DATACMNS-1210 - Polishing.

More fixes of imports. Removed obsolete generics in constructor expressions. Removed a couple of compiler warnings in test cases. Removed assumption for test case to only run on JDK 9.

Original pull request: #259.

Author: odrotbohm

src/main/java/org/springframework/data/mapping/model/BasicPersistentEntity.java

@@ -30,12 +30,23 @@
 import java.util.Optional;
 import java.util.Set;
 import java.util.TreeSet;
-import java.util.concurrent.ConcurrentHashMap;
 import java.util.stream.Collectors;
 
 import org.springframework.core.annotation.AnnotatedElementUtils;
 import org.springframework.data.annotation.TypeAlias;
-import org.springframework.data.mapping.*;
+import org.springframework.data.mapping.Alias;
+import org.springframework.data.mapping.Association;
+import org.springframework.data.mapping.AssociationHandler;
+import org.springframework.data.mapping.IdentifierAccessor;
+import org.springframework.data.mapping.MappingException;
+import org.springframework.data.mapping.PersistentEntity;
+import org.springframework.data.mapping.PersistentProperty;
+import org.springframework.data.mapping.PersistentPropertyAccessor;
+import org.springframework.data.mapping.PreferredConstructor;
+import org.springframework.data.mapping.PropertyHandler;
+import org.springframework.data.mapping.SimpleAssociationHandler;
+import org.springframework.data.mapping.SimplePropertyHandler;
+import org.springframework.data.mapping.TargetAwareIdentifierAccessor;
 import org.springframework.data.util.Lazy;
 import org.springframework.data.util.TypeInformation;
 import org.springframework.lang.Nullable;
@@ -106,8 +117,7 @@ public BasicPersistentEntity(TypeInformation<T> information, @Nullable Comparato
 
 		this.propertyCache = new ConcurrentReferenceHashMap<>();
 		this.annotationCache = new ConcurrentReferenceHashMap<>();
-		this.propertyAnnotationCache = CollectionUtils
-				.toMultiValueMap(new ConcurrentReferenceHashMap<Class<? extends Annotation>, List<P>>());
+		this.propertyAnnotationCache = CollectionUtils.toMultiValueMap(new ConcurrentReferenceHashMap<>());
 		this.propertyAccessorFactory = BeanWrapperPropertyAccessorFactory.INSTANCE;
 		this.typeAlias = Lazy.of(() -> getAliasFromAnnotation(getType()));
 	}

src/test/java/org/springframework/data/mapping/model/BasicPersistentEntityUnitTests.java

@@ -55,7 +55,7 @@
 import org.springframework.data.mapping.context.SampleMappingContext;
 import org.springframework.data.mapping.context.SamplePersistentProperty;
 import org.springframework.data.util.ClassTypeInformation;
-import org.springframework.data.util.Version;
+import org.springframework.lang.Nullable;
 import org.springframework.test.util.ReflectionTestUtils;
 
 /**
@@ -286,19 +286,16 @@ public void getRequiredAnnotationThrowsException() {
 	@Test // DATACMNS-1210
 	public void findAnnotationShouldBeThreadSafe() throws InterruptedException {
 
-		assumeTrue("Requires Java 9",
-				Version.parse(System.getProperty("java.version")).isGreaterThanOrEqualTo(Version.parse("9.0")));
-
 		CountDownLatch latch = new CountDownLatch(2);
 		CountDownLatch syncLatch = new CountDownLatch(1);
+		AtomicBoolean failed = new AtomicBoolean(false);
 
-		final AtomicBoolean failed = new AtomicBoolean(false);
-
-		PersistentEntity<EntityWithAnnotation, T> entity = new BasicPersistentEntity(
+		PersistentEntity<EntityWithAnnotation, T> entity = new BasicPersistentEntity<EntityWithAnnotation, T>(
 				ClassTypeInformation.from(EntityWithAnnotation.class), null) {
 
+			@Nullable
 			@Override
-			public Annotation findAnnotation(Class annotationType) {
+			public <A extends Annotation> A findAnnotation(Class<A> annotationType) {
 
 				try {
 					syncLatch.await();