code: public void doTag()
              throws JspException
      {
          if (hasErrors()) {
              reportErrors();
              return;
          }
  
          JspTag tag = SimpleTagSupport.findAncestorWithClass(this, IAttributeConsumer.class);
          if (!(tag instanceof IAttributeConsumer)) {
              String s = Bundle.getString("Tags_AttributeInvalidParent");
              registerTagError(s, null);
              reportErrors();
              return;
          }
  
          IAttributeConsumer ac = (IAttributeConsumer) tag;
          ac.setAttribute(_name, _value, _facet);
          return;
      }
docs: Add the URL parameter to the Parameter's parent.
  @throws JspException if a JSP exception has occurred