Enhance warning message for missing entity ids.

Author: meistermeier

src/main/java/org/springframework/data/neo4j/core/mapping/DefaultNeo4jPersistentEntity.java

@@ -265,7 +265,8 @@ private void verifyAssociationsWithProperties() {
 		if (this.isRelationshipPropertiesEntity()) {
 			Supplier<String> messageSupplier = () -> String.format(
 					"The class `%s` for the properties of a relationship "
-							+ "is missing a property for the generated, internal ID (`@Id @GeneratedValue Long id`) "
+							+ "is missing a property for the generated, internal ID (`@Id @GeneratedValue Long id` "
+							+ "or `@Id @GeneratedValue String id`) "
 							+ "which is needed for safely updating properties",
 					this.getUnderlyingClass().getName());
 			Assert.state(this.getIdDescription() != null && this.getIdDescription().isInternallyGeneratedId(), messageSupplier);

src/test/java/org/springframework/data/neo4j/core/mapping/Neo4jMappingContextTest.java

@@ -95,7 +95,7 @@ void startupWithoutInternallyGeneratedIDShouldFail() {
 								Arrays.asList(IrrelevantSourceContainer.class, InvalidRelationshipPropertyContainer.class,
 										IrrelevantTargetContainer.class)));
 						schema.initialize();
-					}).withMessage("The class `org.springframework.data.neo4j.core.mapping.Neo4jMappingContextTest$InvalidRelationshipPropertyContainer` for the properties of a relationship is missing a property for the generated, internal ID (`@Id @GeneratedValue Long id`) which is needed for safely updating properties");
+					}).withMessage("The class `org.springframework.data.neo4j.core.mapping.Neo4jMappingContextTest$InvalidRelationshipPropertyContainer` for the properties of a relationship is missing a property for the generated, internal ID (`@Id @GeneratedValue Long id` or `@Id @GeneratedValue String id`) which is needed for safely updating properties");
 		}
 
 		@Test // GH-2214
@@ -107,7 +107,7 @@ void startupWithWrongKindOfGeneratedIDShouldFail() {
 						Arrays.asList(IrrelevantSourceContainer3.class, InvalidRelationshipPropertyContainer2.class,
 								IrrelevantTargetContainer.class)));
 				schema.initialize();
-			}).withMessage("The class `org.springframework.data.neo4j.core.mapping.Neo4jMappingContextTest$InvalidRelationshipPropertyContainer2` for the properties of a relationship is missing a property for the generated, internal ID (`@Id @GeneratedValue Long id`) which is needed for safely updating properties");
+			}).withMessage("The class `org.springframework.data.neo4j.core.mapping.Neo4jMappingContextTest$InvalidRelationshipPropertyContainer2` for the properties of a relationship is missing a property for the generated, internal ID (`@Id @GeneratedValue Long id` or `@Id @GeneratedValue String id`) which is needed for safely updating properties");
 		}
 
 		@Test // GH-2118