code: private String generateConsumerId() {
          UUID uuid = UUID.randomUUID();
          try {
              return format("%s-%d-%s", InetAddress.getLocalHost().getHostName(), //
                      System.currentTimeMillis(),//
                      Long.toHexString(uuid.getMostSignificantBits()).substring(0, 8));
          } catch (UnknownHostException e) {
              try {
                  return format("%s-%d-%s", InetAddress.getLocalHost().getHostAddress(), //
                          System.currentTimeMillis(),//
                          Long.toHexString(uuid.getMostSignificantBits()).substring(0, 8));
              } catch (UnknownHostException ex) {
                  throw new IllegalArgumentException(
                          "can not generate consume id by auto, set the 'consumerid' parameter to fix this");
              }
          }
      }
docs: generate random consumerid ( hostname-currenttime-uuid.sub(8) )
  
  @return random consumerid