Support sub-module maven launchers in multi-module sibling-located projects

[RichMacDonald]

From discussion at #1487, maven launchers seem to be only supported when rooted in the parent module. Launchers in the parent module that reference sub-modules are supported. Launchers in the sub-modules that reference other modules are not supported.

Note: I work with sibling-structure multi-modules only. I am not familiar with the more conventional situation where sub-modules are child folders of the parent module.

The attachment, maven_repo_example.zip, contains three eclipse projects. They should be unzipped "as is", i.e., as sibling folders, then imported into eclipse. The "maven_parent" project is the parent module. "child_1" and "child_2" are sub-module projects.

Run the "maven_parent/parent-compile-success.launch". It performs a "mvn compile" rooted in the maven_parent folder. "Resolve Workspace artifacts" is selected. The operation should succeed.

Run the "child_2/child-compile-failure.launch". It performs a "mvn compile" rooted in the child_2 folder."Resolve Workspace artifacts" is selected. The operation should fail with the following error:

Could not resolve dependencies for project com.groupid.child_2:child_2:jar:0.0.1-SNAPSHOT: The following artifacts could not be resolved: com.groupid.child_1:child_1:jar:0.0.1-SNAPSHOT (absent): Could not find artifact com.groupid.child_1:child_1:jar:0.0.1-SNAPSHOT

Since a sub-module references its parent, and the parent references all sub-modules, all sibling modules should be locatable in principle. It is desirable that launchers rooted in the sub-module should be able to reference sibling modules.

This is particularly significant because this is how eclipse creates and stores its launchers. If a developer wants to run "mvn test" in a child-module, eclipse will store that launcher in the child-module and it will not work. Only when the same launcher is moved to the parent module (and the child module referenced0 will it work.

maven_repo_example.zip