code: public void accept(NetworkHandler handler) {
          ObjectSinkPropagator propagator = objectTypeNode.getObjectSinkPropagator();
  
          handler.startObjectTypeNode(objectTypeNode);
          indexableConstraint = traversePropagator(propagator, handler);
          handler.endObjectTypeNode(objectTypeNode);
      }
docs: Parse the {@link #objectTypeNode}.
  <p/>
  <p>The application can use this method to instruct the OTN parser to begin parsing an {@link ObjectTypeNode}.</p>
  <p/>
  Once a parse is complete, an application may reuse the same Parser object, possibly with a different
  {@link NetworkHandler}.</p>
  
  @param handler handler that will receieve the events generated by this parser
  @see NetworkHandler