The kie workbench was built to be easyly extended. In its core, there is a plugin architecture behind in errai/uberfire.

• Adding a single maven dependency will be enought
  <dependency>
  <groupid>org.drools</groupid>
  <artifactid>kie-wb-artifiact</artifactid>
  <version>6.4.0.Final</version>
  </depedency>

• Create a maven plugin over gwt that
  • avoids all declaration of included packages. This should be done in each gwt module like putting a file in META-INF directory and the plugin would detect that
  • avoids adding all dependencies with adding the <provided> element

• Create a maven artifact that generates all needed maven module to do your own customize workbench
  • The gwt web app module
  • the assembly projects for all application servers
  • a plugin example with front/pojo/service