NIFI-9596: Fix newline bug in JythonScriptRunner

[mattyb149]

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Description of PR

There needs to be a newline after all the modules are added via sys.path.append. Updated unit test to exercise the logic.

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[joewitt]

@mattyb149 Why is it important to remove the header from the test file? Was it critical to verify the scenario under test? If so can we put a comment in that file somewhere indicating this is intentional and/or make it a different test that is so brutally obviously trivial such that a header would be obviously not necessary?

[mattyb149]

Yes I needed a valid Python statement that wasn't valid on the same line as the first line, and a comment is valid. I can add a comment after the first line to indicate such

[joewitt]

ok fair enough. thanks

[MikeThomsen]

+1 LGTM