code: public <P extends PluginRepository<?, ?>> P getPluginManager(Class<?> pluginType) {
          return (P) pluginRepositories.get(pluginType);
      }
docs: Return a plugin repository identified by the plugin interface type.
  
  @param pluginType
  The plugin interface.
  @param <P>
  The plugin type
  @return The {@link com.buschmais.xo.impl.plugin.PluginRepository}.