Model_old : [A,B,C,D]

Model_new : [A,B,C,X]

Model_merged : [A,B,C,D,X]

Model_merged : [A,B,C,X]

   // potentially modifies model2
  public static EObject compare(EObject model1, EObject model2) {
    DiffModel diff = null;
    MatchModel contentMatch = null;
    Map<String, Object> options = new HashMap<String, Object>();
    try {
      // doContentMatch from current model and down
      contentMatch = MatchService.doContentMatch(model1, model2, options);
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
    diff = DiffService.doDiff(contentMatch, false);
    final List<DiffElement> differences = new ArrayList<DiffElement>(diff.getOwnedElements());
    // This will merge all references to the right model (second argument).
    MergeService.merge(differences, true);
    return model2;
  }