findbugs: ignore: findbugs complain of unused field in class.

This is a GWT classes and use to generate code

findbugs reason:
UuF: Unused field (UUF_UNUSED_FIELD)

Change-Id: I536a80c26a03bb263dc6a2e667cfa762fdf29bd5
Signed-off-by: Shahar Havivi <shavivi@redhat.com>