Having a method that raises NotImplementedError is usually not ideal,
since the implementations of the class can't delegate control
through super to the parent or to other classes found in the MRO.
Instead, we mark a priori ReportingHandler as a base class, leaving
the implementation of `publish_event` empty.
Change-Id: Id5c442b6998743b1caffbad627847ee5e88f2982
628e1a2fb0