Use collection name instead type to look up the collection for index creation.

Closes: #4698
Original Pull Request: #4699

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

@@ -209,10 +209,6 @@ public class DefaultIndexOperations implements IndexOperations {
 
 		Assert.notNull(callback, "CollectionCallback must not be null");
 
-		if (type != null) {
-			return mongoOperations.execute(type, callback);
-		}
-
 		return mongoOperations.execute(collectionName, callback);
 	}
 

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/DefaultIndexOperationsUnitTests.java

@@ -43,6 +43,7 @@ import com.mongodb.client.model.IndexOptions;
  * Unit tests for {@link DefaultIndexOperations}.
  *
  * @author Christoph Strobl
+ * @author Mark Paluch
  */
 @ExtendWith(MockitoExtension.class)
 public class DefaultIndexOperationsUnitTests {
@@ -121,6 +122,15 @@ public class DefaultIndexOperationsUnitTests {
 		verify(collection).createIndex(eq(new Document("firstname", "hashed")), any());
 	}
 
+	@Test // GH-4698
+	void shouldConsiderGivenCollectionName() {
+
+		DefaultIndexOperations operations = new DefaultIndexOperations(template, "foo", Jedi.class);
+
+		operations.ensureIndex(HashedIndex.hashed("name"));
+		verify(db).getCollection(eq("foo"), any(Class.class));
+	}
+
 	private DefaultIndexOperations indexOpsFor(Class<?> type) {
 		return new DefaultIndexOperations(template, template.getCollectionName(type), type);
 	}