Introduced LineTransformationOutputStream.Delegating

[jglick]

Split out of #3703.

Proposed changelog entries

• New convenience API: LineTransformationOutputStream.Delegating.
• JENKINS-56995: Properly flushing output from the Maven console annotator.

[daniel-beck]

@jglick

Properly flushing output from the Maven console annotator.

Is this a standalone change (perhaps with Jira issue for the bug), or just adapting to the API addition?

[jglick]

That is a standalone change. While dealing with flush() issues generally, I had searched for LineTransformationOutputStream implementations that neglected to do this right, and found a few including this one. I suppose it could be backportable for the benefit of the pipeline-maven plugin, but the new API would not be there, so it would be a distinct patch for LTS: adding

    @Override
    public void flush() throws IOException {
        out.flush();
    }

[jglick]

Anyway I filed JENKINS-56995 for it just in case.