I believe that jbpm 5.3 is right after the corner.
Drools 5.4 was released today, and if you download droolsjbpm-integration-distribution-5.4.0.Final it will come with jbpm 5.3.
It is already in the jboss maven repository.
My bet is that it will be released today or tomorrow... I just hope the documentation will be available very soon!