code: protected Object postNodeCompletion(Object parent, Object node) {
          for (Closure postNodeCompletionDelegate : getProxyBuilder().getPostNodeCompletionDelegates()) {
              (postNodeCompletionDelegate).call(new Object[]{this, parent, node});
          }
  
          return node;
      }
docs: A hook to allow nodes to be processed once they have had all of their
  children applied and allows the actual node object that represents the
  Markup element to be changed.<br>
  It will call any registered postNodeCompletionDelegates, if you override
  this method be sure to call this impl at the end of your code.
  
  @param node   the current node being processed
  @param parent the parent of the node being processed
  @return the node, possibly new, that represents the markup element