I was using Gradle nightly build from last week to test out composite builds and IDEA integration. I found a problem:
when 2 composite participants have submodule with the same name, only one of those submodules appears in IDEA as a proper Java “module” (e.g. with code to compile, etc.). The other one is just a directory in IDEA. Our workaround was to rename one of the submodules to something else and this helped.
Other than that, composite IDEA experience is FANTASTIC!!!