If you're a developer using Microsoft Windows and you've ever developed a GWT application of any size you've probably encountered the command-line length limitation (http://support.microsoft.com/kb/830473).
The gwt-maven-plugin constructs a command line statement to invoke the GWT compiler containing a list of what can be a very extensive classpath declaration. The length of the command line statement can easily exceed the maximum supported by Microsoft Windows; leaving the developer unable to compile their GWT application without resorting to tricks such as mapping a drive to their local Maven repository thus shortening the classpath entries.
Hopefully this will soon become a thing of the past!
I've submitted a Pull Request to the gwt-maven-plugin project to provide a more concrete solution. With this patch the gwt-maven-plugin is able to compile GWT applications of any size on Microsoft Windows without developers needing to devise tricks.
Until the pull request is accepted and merged you can compile kie-drools-wb or kie-wb by fetching my fork of the gwt-maven-plugin and building it locally. No further changes are then required to compile kie-wb.