A plugin can contribute to the rule engine of another plugin. For example the FbContrib plugin adds rules to the repository "findbugs" defined and executed by the Findbugs plugin (that is an unrealistic example as fbcontrib project was recently merged into the findbugs plugin).
Previously API was different for the two plugins :
The class NewExtendedRepository was used just to forbid plugins to change the repository name (no method #setName(String)).
This brings useless complexity. Both plugins should share the same API. The contributing plugin can optionally set the name. The only important constraint is that the name is set at least once.