DATAMONGO-411 - Double check type of PersistentEntity for index creation.

The Spring container does not check nested generic types of the type parameter of  ApplicationEvent<T>. As T is parameterized in our case as well (PersistentEntity<…, …>) we can code an event listener against that fully parameterized type but might run into ClassCastExceptions as we might get other implementations handed into the method at runtime. We now do an instanceof check to safely invoke checkForIndexes(…) only in case we get the correct event type.

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/index/MongoPersistentEntityIndexCreator.java

@@ -23,6 +23,7 @@ import java.util.concurrent.ConcurrentHashMap;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.context.ApplicationListener;
+import org.springframework.data.mapping.PersistentEntity;
 import org.springframework.data.mapping.PropertyHandler;
 import org.springframework.data.mapping.event.MappingContextEvent;
 import org.springframework.data.mongodb.MongoDbFactory;
@@ -76,7 +77,13 @@ public class MongoPersistentEntityIndexCreator implements
 	 */
 	public void onApplicationEvent(
 			MappingContextEvent<MongoPersistentEntity<MongoPersistentProperty>, MongoPersistentProperty> event) {
-		checkForIndexes(event.getPersistentEntity());
+
+		PersistentEntity<?, ?> entity = event.getPersistentEntity();
+
+		// Double check type as Spring infrastructure does not consider nested generics
+		if (entity instanceof MongoPersistentEntity) {
+			checkForIndexes(event.getPersistentEntity());
+		}
 	}
 
 	protected void checkForIndexes(final MongoPersistentEntity<?> entity) {