FCPPluginClientTracker: Resolve FIXME of JavaDoc'ing the registration requirements at other classes
- Do not document it at the client-side interface as originally request by the FIXME: That interface should be clean of internals stuff, it should be easy to understand by client authors
- Instead, document it at the constructurs of FCPPluginClient. You will have to use the constructors for sure when creating clients so you'll run into the JavaDoc.