NIFI-1856 ExecuteStreamCommand Needs to Consume Standard Error

[rkarthik29]

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[rkarthik29]

added a property to executeSTreamCommand "Redirect Error Output". [log,output stream, error stream]. log is the default.
When set to log, the error stream is captured and output is logged to the Nifi app logs at the warn level.Also, the errors are available in the original stream as an attribute, which is the current behavior.
When set to output stream, the redirecterrorstream is set to true so all errors go to the output streams and are available in the output stream relation
when set to error stream, the error output is forwarded to an errorflowfile which is available in the error stream relationship.The error stream relationship is new.

Added a process.destroyforcibly of the processor unscheduled event.

Checked execute process, it was already capturing the error stream, so no change needed.

[jackowaya]

Happy to see someone looking at this!

The logic looks mostly sound here. There are some stylistic changes that may get you flagged by contribCheck. Can you run mvn -Pcontrib-check clean install to verify that things are good there?

[jackowaya]

I'm not sure if nifi has an import order rule, but generally I try to avoid commits that move a lot of imports around like this.

[jackowaya]

It would be better to hold these strings in static final variables so they can be reused later without fear of mistyping.

Also spacing looks off here. You should run autoformat again.

[rkarthik29]

I did a contrib check and there were no style errors. I agree using final variables would be nicer , will do that.

[mattyb149]

Many of the commits are merge commits, when this PR is merged it can make the commit log fairly messy. Do you mind rebasing your own branch against the latest "upstream" master branch. You may find it helpful to create a branch specifically for this PR, then reset your own master branch to upstream, then you can rebase this branch against master without worrying whether to fetch or pull from upstream in the future. Not a requirement, just a suggestion to help keep things a bit cleaner :)