This commit gives the `maven-use` plugin the ability to consume, as "source", artifacts that were previously built by Maven. This ability is constrained to the existence of a "maven-use" top-level directory in the part's source, which indicates that the plugin should use those binaries directly instead of attempting to build from Java source. To illustrate this behavior, the new integration test builds two "projects": the first, "binaries-source", builds two Java dependencies using the maven-use plugin and copies the generated artifacts as "sources" for the second project, "binaries-consume". This project's third and final part then uses regular Java sources with the Maven plugin to create a fat "application" jar. - [ ] Have you signed the [CLA](http://www.ubuntu.com/legal/contributors/)? - [ ] Have you added an entry to the changelog (`docs/reference/changelog.rst`)? -----