Any way to get IDEA to add *GrailsPlugin.groovy to class path?

When developing a grails plugin in IDEA (I'm using version 10.5.2 on OSX, if it matters), I can't get it to add the *GrailsPlugin.groovy file to the classpath in a way that it can be recognized by unit tests run from the IDE. The tests run fine from the command line using grails test-app; I just want IDEA to be able to run them too.

The problem is that the *GrailsPlugin.groovy file is at the top level directory in the plugin, which is not marked as a source directory in IDEA. I definitely don't want to make it a source folder, since that will screw up lots of things such as the package path to all of my regular source files (amongst many other issues).
I've tried adding *GrailsPlugin.groovy to my Settings->Compiler Resource Patterns, but to no avail. Since the file isn't in a source folder, it's ignored.
I tried creating a source folder that has a symlink to the *GrailsPlugin.groovy file, but that introduces all kinds of synchronization issues.

Anyone have any ideas?