DATACMNS-1364 - Polishing.

Use weak references in annotation and property annotation cache to retain references until the last GC root is cleared. Remove trailing whitespaces. Reformat.

Original pull request: #304.

Author: mp911de

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

@@ -38,6 +38,7 @@
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.ConcurrentReferenceHashMap;
+import org.springframework.util.ConcurrentReferenceHashMap.ReferenceType;
 import org.springframework.util.MultiValueMap;
 import org.springframework.util.StringUtils;
 
@@ -105,8 +106,9 @@ public BasicPersistentEntity(TypeInformation<T> information, @Nullable Comparato
 		this.associations = comparator == null ? new HashSet<>() : new TreeSet<>(new AssociationComparator<>(comparator));
 
 		this.propertyCache = new HashMap<>();
-		this.annotationCache = new ConcurrentReferenceHashMap<>();
-		this.propertyAnnotationCache = CollectionUtils.toMultiValueMap(new ConcurrentReferenceHashMap<>());
+		this.annotationCache = new ConcurrentReferenceHashMap<>(16, ReferenceType.WEAK);
+		this.propertyAnnotationCache = CollectionUtils
+				.toMultiValueMap(new ConcurrentReferenceHashMap<>(16, ReferenceType.WEAK));
 		this.propertyAccessorFactory = BeanWrapperPropertyAccessorFactory.INSTANCE;
 		this.typeAlias = Lazy.of(() -> getAliasFromAnnotation(getType()));
 		this.isNewStrategy = Lazy.of(() -> Persistable.class.isAssignableFrom(information.getType()) //