Github user zhangminglei commented on the issue:
https://github.com/apache/flink/pull/6075
Thanks @hequn8128. You are very correct! It is more reasonable to put the
ORC related classes into there ~, like @StephanEwen said, at the very least.
make them optional. As refers to implement the ```CheckpointedFuntion```, I
would not think it is necessary for it since ```BucketingSink``` have already
implemented that and we just use the orc writer in this way like
```bucketingSink.setWriter(new OrcFileWriter<>(orcSchemaString))```.Also, we
can take a look on ```SequenceFileWriter``` and ```StringWriter``` both do not
implement ```CheckpointedFuntion```.
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