GWT module xml source element to specify single class - gwt

Question

I have a GWT application (FooGwtApp) and a library module (FooLib) used as a dependency in FooGwtApp. The package structure of FooLib looks like this:
packageFoo.ImportantClass
packageFoo.UnimportantClass
packageBar.OtherClass
I want ImportantClass (and only ImportantClass) to be compiled to JS by the GWT compiler. Moving ImportantClass to another package is not an option.
I created ImportantClass.gwt.xml within packageFoo with the following content:
<module>
<inherits name="com.google.gwt.user.User"/>
<source path="" includes="**/ImportantClass*"/>
</module>
Next I put an inherited reference to the ImportantClass module definition in FooGwtApp.gwt.xml (this seems to work: the IDE recognizes it, and is able to parse the reference to ImportantClass.gwt.xml).
Now If I put references to ImportantClass into FooGwtApp's client code, the GWT compiler fails, because it does not find ImportantClass on the source path:
No source code is available for type packageFoo.ImportantClass; did you forget to inherit a required module?
I likely messed up sommething in the source path / includes attribute in ImportantClass.gwt.xml - either defining the current package as root package with path="" is not a valid notation or something's wrong with the includes attribute. Or both. Or neither.
Can you give me a clue about where it all went wrong?

Answer 1

It turns out the problem was not in ImportantClass.gwt.xml, but in other Maven related stuff:
ImportantClass.gwt.xml should be placed under src/main/resources/packageFoo, not src/main/java/packageFoo, otherwise it won't be packaged into the binary jar.
GWT compiler compiles from Java source to Javascript source. This means we don't just need ImportantClass.class in FooLib.jar, but also its source. Best solution for this is to use maven-source-plugin in FooLib's pom.xml and also to import the FooLib dependency into FooGwtApp with sources classifier.
On the latter topic, see the following SO answers:
Maven: Distribute source code with with jar-with-dependencies
How to properly include Java sources in Maven?
After fixing the above problems, the source path declaration present in the question works.