Added deleteInBatch method to JpaRepository.

Reverted implementation of delete(Iterable<T> entities) to iterate over the entities as creating a query can cause the persistence provider to choke on really large entity sets. Beyond that triggering a query would require us to clear the persistence context which might not be wanted in every case. Thus an additional method deleteInBatch(Iterable<T> entities) especially available on the JpaRepository interface now triggers the query but clearly states the assumptions and side effects in the JavaDoc. Removed some obsolete finals and an obsolete method.

src/test/java/org/springframework/data/jpa/repository/UserRepositoryTests.java

@@ -225,6 +225,18 @@ public class UserRepositoryTests {
     }
 
 
+    @Test
+    public void batchDeleteColletionOfEntities() {
+
+        flushTestUsers();
+
+        long before = repository.count();
+
+        repository.deleteInBatch(Arrays.asList(firstUser, secondUser));
+        assertThat(repository.count(), is(before - 2));
+    }
+
+
     @Test
     public void deleteEmptyCollectionDoesNotDeleteAnything() {