code: protected LabelNode getLabelNode(final Label l) {
          if (!(l.info instanceof LabelNode)) {
              l.info = new LabelNode();
          }
          return (LabelNode) l.info;
      }
docs: Returns the LabelNode corresponding to the given Label. Creates a new
  LabelNode if necessary. The default implementation of this method uses
  the {@link Label#info} field to store associations between labels and
  label nodes.
  
  @param l
  a Label.
  @return the LabelNode corresponding to l.