I2b065a8ec exposed sources in GWT UI plugin API. Given that classpath
generation tool chain depends on GWT UI plugin API, the transitive
closure was now included in the Eclipse classpath. But we don't want
to include the source JARs, because the source directories themself
already included.
Reported-By: Hector Oswaldo Caballero <hector.caballero@ericsson.com>
Change-Id: Iaef7eecba48f08f327dce6af258d45408850d859