for (Iterator<Position> i = positions.iterator(); i.hasNext();) {
      Object position = i.next();
      additionsMap.put(new ProjectionAnnotation(), position);
    }
    if ((deletions.length != 0 || additionsMap.size() != 0))
      annotationModel.modifyAnnotations(deletions, additionsMap,
          new Annotation[] {});
  }
  @SuppressWarnings("unchecked")
  private Annotation[] computeDifferences(ArrayList<Position> additions,