code: public static WxCpXmlMessage fromEncryptedXml(
        String encryptedXml,
        WxCpConfigStorage wxCpConfigStorage,
        String timestamp, String nonce, String msgSignature) {
      WxCpCryptUtil cryptUtil = new WxCpCryptUtil(wxCpConfigStorage);
      String plainText = cryptUtil.decrypt(msgSignature, timestamp, nonce, encryptedXml);
      return fromXml(plainText);
    }
docs: 从加密字符串转换
  
  @param encryptedXml
  @param wxCpConfigStorage
  @param timestamp
  @param nonce
  @param msgSignature
  @return