public SortedSet<String> plugins(){
  SortedSet<String> r=new TreeSet<>();
  for (  NamePair p : items.keySet()) {
    r.add(p.pluginName);
  }
  return Collections.unmodifiableSortedSet(r);
}

public SortedSet < String > plugins ( ) { SortedSet < String > r = new TreeSet < > ( ) ; for ( NamePair p : items . keySet ( ) ) { r . add ( p . pluginName ) ; } return Collections . unmodifiableSortedSet ( r ) ; }
get the names of all running plugins supplying this type .
