public Ranking getAutoTransformerRanking(Transformer transformer) {
   for (AutoRanking autoRanking : autoRankings) {
     if (autoRanking.getTransformer().equals(transformer)) {
       return autoRanking.getRanking();
     }
   }
   return null;
 }
 public void removeAutoRanking(Transformer transformer) {
   for (AutoRanking r : autoRankings.toArray(new AutoRanking[0])) {
     if (r.getTransformer().equals(transformer)) {
       autoRankings.remove(r);
     }
   }
   if (autoRankings.isEmpty()) {
     autoTransformer.stop();
   }
 }