code: private static String[] decodeAuthAmqPlain(String response) {
          Logger logger = LoggerFactory.getLogger(SERVICE_AMQP_PROXY_LOGGER);
          
          String[] credentials = null;
  
          if ((response != null) && (response.trim().length() > 0)) {
              ByteBuffer buffer = ByteBuffer.wrap(response.getBytes());
              
              @SuppressWarnings("unused")
              String loginKey = getShortString(buffer);
              @SuppressWarnings("unused")
              AmqpType ltype = getType(buffer);
              String username = getLongString(buffer);
              
              @SuppressWarnings("unused")
              String passwordKey = getShortString(buffer);
              @SuppressWarnings("unused")
              AmqpType ptype = getType(buffer);
              String password = getLongString(buffer);
  
              if (logger.isDebugEnabled()) {
                  String s = ".decodeAuthAmqPlain(): Username = " + username;
                  logger.debug(CLASS_NAME + s);
              }
  
              credentials = new String[] { username, password };
          }
          
          return credentials;
      }
docs: the 1st element is the password.