code: AtomSymbol addAnnotation(TextOutline annotation) {
          List<TextOutline> newAnnotations = new ArrayList<TextOutline>(annotationAdjuncts);
          newAnnotations.add(annotation);
          return new AtomSymbol(element, adjuncts, newAnnotations, alignment, hull);
      }
docs: Include a new annotation adjunct in the atom symbol.
  
  @param annotation the new annotation adjunct
  @return a new AtomSymbol instance including the annotation adjunct