public static String choose(final String encryptMode, final String password) {
        if ("MD5".equals(encryptMode)) {
            return md5(password);
        }
        return password;
    }
choose encrypt mode.
@param encryptMode encryptMode
@param password password
@return encrypt password.
shenyu-protocol/shenyu-protocol-mqtt/src/main/java/org/apache/shenyu/protocol/mqtt/utils/EncryptUtil.java