fix: Assume Values.NULL in all cases where id values are literal null.

Closes #2710

Author: michael-simons

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

@@ -48,6 +48,7 @@
 import org.neo4j.cypherdsl.core.renderer.Configuration;
 import org.neo4j.cypherdsl.core.renderer.Renderer;
 import org.neo4j.driver.Value;
+import org.neo4j.driver.Values;
 import org.neo4j.driver.exceptions.NoSuchRecordException;
 import org.neo4j.driver.summary.ResultSummary;
 import org.neo4j.driver.types.Entity;
@@ -308,16 +309,23 @@ entityMetaData, convertIdValues(entityMetaData.getRequiredIdProperty(), ids)))
 				.getResults();
 	}
 
-	private Object convertIdValues(@Nullable Neo4jPersistentProperty idProperty, Object idValues) {
+	private Object convertIdValues(@Nullable Neo4jPersistentProperty idProperty, @Nullable Object idValues) {
 
 		if (idProperty != null && ((Neo4jPersistentEntity<?>) idProperty.getOwner()).isUsingInternalIds()) {
 			return idValues;
 		}
 
-		return neo4jMappingContext.getConversionService().writeValue(idValues, TypeInformation.of(idValues.getClass()),
-				idProperty == null ? null : idProperty.getOptionalConverter());
+		if (idValues != null) {
+			return neo4jMappingContext.getConversionService().writeValue(idValues, TypeInformation.of(idValues.getClass()), idProperty == null ? null : idProperty.getOptionalConverter());
+		} else if (idProperty != null) {
+			return neo4jMappingContext.getConversionService().writeValue(idValues, idProperty.getTypeInformation(), idProperty.getOptionalConverter());
+		} else {
+			// Not much we can convert here
+			return Values.NULL;
+		}
 	}
 
+
 	@Override
 	public <T> T save(T instance) {
 

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

@@ -19,6 +19,7 @@
 import static org.neo4j.cypherdsl.core.Cypher.asterisk;
 import static org.neo4j.cypherdsl.core.Cypher.parameter;
 
+import org.neo4j.driver.Values;
 import org.springframework.data.neo4j.core.mapping.IdDescription;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
@@ -307,15 +308,20 @@ public <T> Mono<ExecutableQuery<T>> toExecutableQuery(Class<T> domainType,
 		return createExecutableQuery(domainType, null, queryFragmentsAndParameters);
 	}
 
+	private Object convertIdValues(@Nullable Neo4jPersistentProperty idProperty, @Nullable Object idValues) {
 
-	private Object convertIdValues(@Nullable Neo4jPersistentProperty idProperty, Object idValues) {
-
-		if (((Neo4jPersistentEntity<?>) idProperty.getOwner()).isUsingInternalIds()) {
+		if (idProperty != null && ((Neo4jPersistentEntity<?>) idProperty.getOwner()).isUsingInternalIds()) {
 			return idValues;
 		}
 
-		return neo4jMappingContext.getConversionService().writeValue(idValues,
-				TypeInformation.of(idValues.getClass()), idProperty == null ? null : idProperty.getOptionalConverter());
+		if (idValues != null) {
+			return neo4jMappingContext.getConversionService().writeValue(idValues, TypeInformation.of(idValues.getClass()), idProperty == null ? null : idProperty.getOptionalConverter());
+		} else if (idProperty != null) {
+			return neo4jMappingContext.getConversionService().writeValue(idValues, idProperty.getTypeInformation(), idProperty.getOptionalConverter());
+		} else {
+			// Not much we can convert here
+			return Values.NULL;
+		}
 	}
 
 	@Override