Fixes for #2408 and #2409.

pom.xml

@@ -5,7 +5,7 @@
 
 	<groupId>org.springframework.data</groupId>
 	<artifactId>spring-data-commons</artifactId>
-	<version>2.6.0-SNAPSHOT</version>
+	<version>2.6.0-GH-2408-2409-SNAPSHOT</version>
 
 	<name>Spring Data Core</name>
 

src/main/java/org/springframework/data/mapping/PersistentProperty.java

@@ -70,9 +70,21 @@ public interface PersistentProperty<P extends PersistentProperty<P>> {
 	 * {@link Map}'s value type transparently.
 	 *
 	 * @return
+	 * @deprecated since 2.6 for removal in 3.0. Use {@link #getPersistentEntityTypeInformation()} instead.
 	 */
+	@Deprecated
 	Iterable<? extends TypeInformation<?>> getPersistentEntityTypes();
 
+	/**
+	 * Returns the {@link TypeInformation} if the property references a {@link PersistentEntity}. Will return
+	 * {@literal null} in case it refers to a simple type. Will return {@link Collection}'s component type or the
+	 * {@link Map}'s value type transparently.
+	 *
+	 * @return
+	 * @since 2.6
+	 */
+	Iterable<? extends TypeInformation<?>> getPersistentEntityTypeInformation();
+
 	/**
 	 * Returns the getter method to access the property value if available. Might return {@literal null} in case there is
 	 * no getter method with a return type assignable to the actual property's type.
@@ -395,6 +407,19 @@ default boolean hasActualTypeAnnotation(Class<? extends Annotation> annotationTy
 	@Nullable
 	Class<?> getAssociationTargetType();
 
+	/**
+	 * Return the type the property refers to in case it's an association, i.e. {@link #isAssociation()} returns
+	 * {@literal true}. That means, that implementations <em>must</em> return a non-{@literal null} value from this method
+	 * in that case. We also recommend to return {@literal null} for non-associations right away to establish symmetry
+	 * between this method and {@link #isAssociation()}.
+	 *
+	 * @return the type the property refers to in case it's an association, i.e. {@link #isAssociation()} returns
+	 *         {@literal true}.
+	 * @since 2.6
+	 */
+	@Nullable
+	TypeInformation<?> getAssociationTargetTypeInformation();
+
 	/**
 	 * Returns a {@link PersistentPropertyAccessor} for the current property's owning value.
 	 *

src/main/java/org/springframework/data/mapping/context/AbstractMappingContext.java

@@ -33,7 +33,6 @@
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
-
 import org.springframework.beans.BeanUtils;
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.InitializingBean;
@@ -576,7 +575,7 @@ private void createAndRegisterProperty(Property input) {
 				return;
 			}
 
-			property.getPersistentEntityTypes().forEach(it -> {
+			property.getPersistentEntityTypeInformation().forEach(it -> {
 
 				if (shouldCreatePersistentEntityFor(it)) {
 					addPersistentEntity(it);

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

@@ -164,6 +164,15 @@ public TypeInformation<?> getTypeInformation() {
 	 */
 	@Override
 	public Iterable<? extends TypeInformation<?>> getPersistentEntityTypes() {
+		return getPersistentEntityTypeInformation();
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mapping.PersistentProperty#getPersistentEntityTypeInformation()
+	 */
+	@Override
+	public Iterable<? extends TypeInformation<?>> getPersistentEntityTypeInformation() {
 
 		if (isMap() || isCollectionLike()) {
 			return entityTypeInformation.get();
@@ -279,11 +288,21 @@ public Association<P> getAssociation() {
 	@Override
 	public Class<?> getAssociationTargetType() {
 
-		TypeInformation<?> result = associationTargetType.getNullable();
+		TypeInformation<?> result = getAssociationTargetTypeInformation();
 
 		return result != null ? result.getType() : null;
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mapping.PersistentProperty#getAssociationTargetTypeInformation()
+	 */
+	@Nullable
+	@Override
+	public TypeInformation<?> getAssociationTargetTypeInformation() {
+		return associationTargetType.getNullable();
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.mapping.PersistentProperty#isCollectionLike()
@@ -356,11 +375,7 @@ public Class<?> getMapValueType() {
 	 */
 	@Override
 	public Class<?> getActualType() {
-
-		TypeInformation<?> targetType = associationTargetType.getNullable();
-		TypeInformation<?> result = targetType == null ? information.getRequiredActualType() : targetType;
-
-		return result.getType();
+		return getActualTypeInformation().getType();
 	}
 
 	/*
@@ -375,6 +390,12 @@ protected Property getProperty() {
 		return this.property;
 	}
 
+	protected TypeInformation<?> getActualTypeInformation() {
+
+		TypeInformation<?> targetType = associationTargetType.getNullable();
+		return targetType == null ? information.getRequiredActualType() : targetType;
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see java.lang.Object#equals(java.lang.Object)
@@ -415,9 +436,8 @@ public String toString() {
 
 	private Set<TypeInformation<?>> detectEntityTypes(SimpleTypeHolder simpleTypes) {
 
-		TypeInformation<?> typeToStartWith = ASSOCIATION_TYPE != null && ASSOCIATION_TYPE.isAssignableFrom(rawType)
-				? information.getComponentType()
-				: information;
+		TypeInformation<?> typeToStartWith = getAssociationTargetTypeInformation();
+		typeToStartWith = typeToStartWith == null ? information : typeToStartWith;
 
 		Set<TypeInformation<?>> result = detectEntityTypes(typeToStartWith);
 

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

@@ -37,9 +37,11 @@
 import org.springframework.data.mapping.MappingException;
 import org.springframework.data.mapping.PersistentEntity;
 import org.springframework.data.mapping.PersistentProperty;
+import org.springframework.data.util.ClassTypeInformation;
 import org.springframework.data.util.Lazy;
 import org.springframework.data.util.Optionals;
 import org.springframework.data.util.StreamUtils;
+import org.springframework.data.util.TypeInformation;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
@@ -74,7 +76,7 @@ public abstract class AnnotationBasedPersistentProperty<P extends PersistentProp
 			&& (isAnnotationPresent(Reference.class) || super.isAssociation()));
 	private final Lazy<Boolean> isId = Lazy.of(() -> isAnnotationPresent(Id.class));
 	private final Lazy<Boolean> isVersion = Lazy.of(() -> isAnnotationPresent(Version.class));
-	private final Lazy<Class<?>> associationTargetType = Lazy.of(() -> {
+	private final Lazy<TypeInformation<?>> associationTargetType = Lazy.of(() -> {
 
 		if (!isAssociation()) {
 			return null;
@@ -83,8 +85,8 @@ public abstract class AnnotationBasedPersistentProperty<P extends PersistentProp
 		return Optional.of(Reference.class) //
 				.map(this::findAnnotation) //
 				.map(Reference::to) //
-				.map(it -> !Class.class.equals(it) ? it : getActualType()) //
-				.orElseGet(() -> super.getAssociationTargetType());
+				.map(it -> !Class.class.equals(it) ? ClassTypeInformation.from(it) : getActualTypeInformation()) //
+				.orElseGet(() -> super.getAssociationTargetTypeInformation());
 	});
 
 	/**
@@ -295,11 +297,11 @@ public boolean usePropertyAccess() {
 
 	/*
 	 * (non-Javadoc)
-	 * @see org.springframework.data.mapping.PersistentProperty#getAssociationTargetType()
+	 * @see org.springframework.data.mapping.model.AbstractPersistentProperty#getAssociationTargetTypeInformation()
 	 */
 	@Nullable
 	@Override
-	public Class<?> getAssociationTargetType() {
+	public TypeInformation<?> getAssociationTargetTypeInformation() {
 		return associationTargetType.getNullable();
 	}
 

src/test/java/org/springframework/data/mapping/context/AbstractMappingContextIntegrationTests.java

@@ -113,7 +113,7 @@ protected T createPersistentProperty(Property property, BasicPersistentEntity<Ob
 
 			when(prop.getTypeInformation()).thenReturn(owner.getTypeInformation());
 			when(prop.getName()).thenReturn(property.getName());
-			when(prop.getPersistentEntityTypes()).thenReturn(Collections.EMPTY_SET);
+			when(prop.getPersistentEntityTypeInformation()).thenReturn(Collections.EMPTY_SET);
 
 			try {
 				Thread.sleep(200);

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

@@ -73,7 +73,7 @@ void discoversComponentTypeCorrectly() {
 
 	@Test // DATACMNS-101
 	void returnsNestedEntityTypeCorrectly() {
-		assertThat(getProperty(TestClassComplex.class, "testClassSet").getPersistentEntityTypes()).isEmpty();
+		assertThat(getProperty(TestClassComplex.class, "testClassSet").getPersistentEntityTypeInformation()).isEmpty();
 	}
 
 	@Test // DATACMNS-132
@@ -198,7 +198,7 @@ void considersCollectionPropertySimpleIfComponentTypeIsSimple() {
 	void doesNotConsiderPropertyWithTreeMapMapValueAnEntity() {
 
 		SamplePersistentProperty property = getProperty(TreeMapWrapper.class, "map");
-		assertThat(property.getPersistentEntityTypes()).isEmpty();
+		assertThat(property.getPersistentEntityTypeInformation()).isEmpty();
 		assertThat(property.isEntity()).isFalse();
 	}
 
@@ -233,7 +233,7 @@ void detectsJMoleculesAssociation() {
 
 		assertThat(property.isAssociation()).isTrue();
 		assertThat(property.getAssociationTargetType()).isEqualTo(JMoleculesAggregate.class);
-		assertThat(property.getPersistentEntityTypes())
+		assertThat(property.getPersistentEntityTypeInformation())
 				.extracting(it -> it.getType())
 				.containsExactly((Class) JMoleculesAggregate.class);
 	}

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

@@ -47,6 +47,7 @@
 import org.springframework.data.mapping.PersistentProperty;
 import org.springframework.data.mapping.context.SampleMappingContext;
 import org.springframework.data.mapping.context.SamplePersistentProperty;
+import org.springframework.data.util.ClassTypeInformation;
 import org.springframework.lang.Nullable;
 import org.springframework.test.util.ReflectionTestUtils;
 
@@ -318,6 +319,16 @@ void detectsJMoleculesAssociation() {
 		assertThat(property.getAssociationTargetType()).isEqualTo(JMoleculesAggregate.class);
 	}
 
+	@Test // GH-2409
+	void exposesAssociationTargetClassAsPersistentEntityType() {
+
+		SamplePersistentProperty property = getProperty(WithReferences.class, "toSample");
+
+		assertThat(property.getPersistentEntityTypeInformation()) //
+				.isNotEmpty() //
+				.allMatch(it -> it.equals(ClassTypeInformation.from(Sample.class)));
+	}
+
 	@SuppressWarnings("unchecked")
 	private Map<Class<? extends Annotation>, Annotation> getAnnotationCache(SamplePersistentProperty property) {
 		return (Map<Class<? extends Annotation>, Annotation>) ReflectionTestUtils.getField(property, "annotationCache");