code: @Override
      public int doEndTag() throws JspException {
          SQLExecutionTag parent = (SQLExecutionTag)
                  findAncestorWithClass(this, SQLExecutionTag.class);
          if (parent == null) {
              throw new JspTagException(
                      Resources.getMessage("SQL_PARAM_OUTSIDE_PARENT"));
          }
  
          if (value != null) {
              convertValue();
          }
  
          parent.addSQLParameter(value);
          return EVAL_PAGE;
      }
docs: Tag logic