Github user GJL commented on the issue:
https://github.com/apache/flink/pull/5216
There are some checkstyle violations:
```
[ERROR]
src/main/java/org/apache/flink/yarn/cli/YarnApplicationStatusMonitor.java:[33,8]
(imports) UnusedImports: Unused import:
java.util.concurrent.ScheduledExecutorService.
[ERROR] src/main/java/org/apache/flink/yarn/YarnClusterClient.java:[46,8]
(imports) UnusedImports: Unused import:
org.apache.hadoop.yarn.client.api.YarnClient.
```---
