public boolean isLoaded(String name){
  PluginHolder<T> result=registry.get(name);
  if (result == null)   return false;
  return result.isLoaded();
}

public boolean isLoaded ( String name ) { PluginHolder < T > result = registry . get ( name ) ; if ( result == null ) return false ; return result . isLoaded ( ) ; }
to check if a plugin by a specified name is already loaded
