code: public UNode toDoc() {
          UNode paramNode = UNode.createMapNode(m_name);
          if (!Utils.isEmpty(m_type)) {
              paramNode.addValueNode("_type", m_type);
          }
          if (m_isRequired) {
              paramNode.addValueNode("_required", Boolean.toString(m_isRequired));
          }
          if (m_parameters.size() > 0) {
              for (RESTParameter param : m_parameters) {
                  paramNode.addChildNode(param.toDoc());
              }
          }
          return paramNode;
      }
docs: Serialize this RESTParameter into a UNode tree and return the root node.
  
  @return  Root {@link UNode} of the serialized tree.