code: public static MpNewsGetHtmlResult mpNewsGetHtml(String accessToken, MpNewsGetHtml mpnews) {
  		return mpNewsGetHtml(accessToken, JsonUtil.toJSONString(mpnews));
  	}
docs: 图文消息群发卡券素材
  @param accessToken accessToken
  @param mpnews mpnews
  @return result