https://github.com/apache/flink/pull/6521/files/66c3bd5d52a5e4af1f83406035b95774e8b6f636#diff-680b30ea43d3038c905b1036011bbe30
https://github.com/apache/flink/pull/6521/files/66c3bd5d52a5e4af1f83406035b95774e8b6f636#diff-ca950f8edf6904e1be268f6ef8f27991
https://issues.apache.org/jira/browse/FLINK-5315
https://github.com/apache/flink/pull/6521#discussion_r211234350
https://github.com/apache/flink/pull/5940