GH-2318 - Include entities of relationship properties in id cache.

Closes #2318

Author: meistermeier

src/main/java/org/springframework/data/neo4j/core/Neo4jTemplate.java

@@ -750,6 +750,10 @@ private <T> T processNestedRelations(Neo4jPersistentEntity<?> sourceEntity, Pers
 					savedEntity = saveRelatedNode(newRelatedObject, targetEntity, includeProperty, currentPropertyPath);
 					relatedInternalId = savedEntity.id();
 					stateMachine.markValueAsProcessed(relatedValueToStore, relatedInternalId);
+					if (relatedValueToStore instanceof MappingSupport.RelationshipPropertiesWithEntityHolder) {
+						Object entity = ((MappingSupport.RelationshipPropertiesWithEntityHolder) relatedValueToStore).getRelatedEntity();
+						stateMachine.markValueAsProcessedAs(entity, relatedInternalId);
+					}
 				}
 
 				PersistentPropertyAccessor<?> targetPropertyAccessor = targetEntity.getPropertyAccessor(newRelatedObject);

src/main/java/org/springframework/data/neo4j/core/ReactiveNeo4jTemplate.java

@@ -848,7 +848,13 @@ private <T> Mono<T> processNestedRelations(Neo4jPersistentEntity<?> sourceEntity
 										.map(id -> Tuples.of(id, new Long[1]));
 							} else {
 								queryOrSave = saveRelatedNode(newRelatedObject, targetEntity, includeProperty, currentPropertyPath)
-										.doOnNext(entity -> stateMachine.markValueAsProcessed(relatedValueToStore, entity.id()))
+										.doOnNext(entity -> {
+											stateMachine.markValueAsProcessed(relatedValueToStore, entity.id());
+											if (relatedValueToStore instanceof MappingSupport.RelationshipPropertiesWithEntityHolder) {
+												Object value = ((MappingSupport.RelationshipPropertiesWithEntityHolder) relatedValueToStore).getRelatedEntity();
+												stateMachine.markValueAsProcessedAs(value, entity.id());
+											}
+										})
 										.map(entity -> {
 											Long version = targetEntity.hasVersionProperty() ?
 													entity.get(targetEntity.getVersionProperty().getPropertyName()).asLong() :

src/main/java/org/springframework/data/neo4j/core/mapping/NestedRelationshipProcessingStateMachine.java

@@ -25,6 +25,7 @@
 import java.util.concurrent.locks.ReentrantReadWriteLock;
 
 import org.apiguardian.api.API;
+import org.springframework.lang.NonNull;
 import org.springframework.lang.Nullable;
 
 /**
@@ -164,9 +165,12 @@ public void markValueAsProcessed(Object valueToStore, Long internalId) {
 
 		try {
 			write.lock();
+			Object value = extractRelatedValueFromRelationshipProperties(valueToStore);
 			this.processedObjects.add(valueToStore);
+			this.processedObjects.add(value);
 			if (internalId != null) {
 				this.processedObjectsIds.put(valueToStore, internalId);
+				this.processedObjectsIds.put(value, internalId);
 			}
 		} finally {
 			write.unlock();
@@ -180,7 +184,13 @@ public void markValueAsProcessed(Object valueToStore, Long internalId) {
  	 * @return processed yes (true) / no (false)
 	 */
 	public boolean hasProcessedValue(Object value) {
-		return processedObjects.contains(value) || processedObjectsAlias.containsKey(value);
+		try {
+			read.lock();
+			Object valueToCheck = extractRelatedValueFromRelationshipProperties(value);
+			return processedObjects.contains(valueToCheck) || processedObjectsAlias.containsKey(valueToCheck);
+		} finally {
+			read.unlock();
+		}
 	}
 
 	/**
@@ -209,8 +219,9 @@ public void markValueAsProcessedAs(Object relatedValueToStore, Object bean) {
 	public Long getInternalId(Object object) {
 		try {
 			read.lock();
-			Long possibleId = processedObjectsIds.get(object);
-			return possibleId != null ? possibleId : processedObjectsIds.get(processedObjectsAlias.get(object));
+			Object valueToCheck = extractRelatedValueFromRelationshipProperties(object);
+			Long possibleId = processedObjectsIds.get(valueToCheck);
+			return possibleId != null ? possibleId : processedObjectsIds.get(processedObjectsAlias.get(valueToCheck));
 		} finally {
 			read.unlock();
 		}
@@ -234,4 +245,14 @@ private boolean hasProcessedAllOf(@Nullable Collection<?> valuesToStore) {
 		return processedObjects.containsAll(valuesToStore);
 	}
 
+	@NonNull
+	private Object extractRelatedValueFromRelationshipProperties(Object valueToStore) {
+		Object value;
+		if (valueToStore instanceof MappingSupport.RelationshipPropertiesWithEntityHolder) {
+			value = ((MappingSupport.RelationshipPropertiesWithEntityHolder) valueToStore).getRelatedEntity();
+		} else {
+			value = valueToStore;
+		}
+		return value;
+	}
 }