Github user GJL commented on a diff in the pull request:
https://github.com/apache/flink/pull/4889#discussion_r157468208
--- Diff:
flink-test-utils-parent/flink-test-utils-junit/src/main/java/org/apache/flink/testutils/category/Flip6.java
---
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.testutils.category;
+
+/**
+ * Category marker interface for Junit.
+ */
+public interface Flip6 {
--- End diff --
nit: This is an interface, but `OldAndFlip6 ` is a class.
nit: Maybe include *flip6* in the javadoc, e.g., *Category marker interface
for Flip6 Junit tests.*
---
