code: public int doStartTag() throws JspException
      {
          if (_rolloverImage != null && getJavaScriptAttribute(ONMOUSEOVER) == null) {
              // cause the roll over script to be inserted
              WriteRenderAppender writer = new WriteRenderAppender(pageContext);
              ScriptRequestState srs = ScriptRequestState.getScriptRequestState((HttpServletRequest) pageContext.getRequest());
              srs.writeFeature(getScriptReporter(), writer, CoreScriptFeature.ROLLOVER, true, false, null);
          }
  
          return EVAL_BODY_BUFFERED;
      }
docs: Insert rollover javascript.
  <p>
  Support for indexed property since Struts 1.1
  @throws JspException if a JSP exception has occurred