There are a multiple slf4j versions. Align all into 1.7.2
updated with http://git.app.eng.bos.redhat.com/?p=errai/errai.git;a=commit;h=663c17dcb9f2501df7199ade8472ccd19d389722
Correct commit is http://git.app.eng.bos.redhat.com/?p=errai/errai.git;a=commitdiff;h=612e73abc2c88642dc68554d128093ca0c7c6571
Verified in WFK 2.3.0.CR1