Fixing JENKINS-16847 MultiJob Support

[rsennewald]

-Added a new Build Selector called MultiJobBuildSelector.
-If selected, this will make the Copy Artifact Plugin look
for an artifact from that job's build which was part of the
current MultiJobBuild.
-This selector will work properly if you configure it with
a MultiJobProject which has a PhaseJob that archives an
artifact that you want to retrieve as part of the MultiJob.
-This selector will also work if you configure it to Copy an
Artifact from another Phase Job which was part of the
current MultiJob Build.
-Added tests to ensure this functionality works as expected.
-Adds MultiJob Plugin as a dependency.

[daniel-beck]

Not optional?

[rsennewald]

What do you mean not optional? What specifically?

[daniel-beck]

Why not add this to MultiJob? Copy Artifacts has three times the installations after all, so that seems to be a more logical place to store the integration (I expect a higher percentage of MultiJob users have Copy Artifact than vice versa).

[rsennewald]

This functionality could be added to MultiJob I suppose, I didn't think about that. I could make it part of the Phase Job Configuration piece to grab an artifact from another Phase Job and then add an option to Copy an Artifact from Phase Job as a Build step for the MultiJob as well. Is this what you were thinking?

[daniel-beck]

No, you should be able to add an optional dependency from MJ to CA, and just move your new Build Selector there. Would appear the same to users, but implemented in MJ.

[rsennewald]

@daniel-beck Thank you for your recommendation. After some thought and consideration I will be moving this to the MultiJob Plugin and add the Copy Artifact Plugin as an Optional Dependency there. Then, only if you have both installed, you'll get my newly added option as I would prefer it to be anyway.