code: protected void checkGETPUTSupport()
          throws ServerException, IOException
      {
          if (!isFeatureSupported(FeatureList.GETPUT)) {
              throw new ServerException(ServerException.UNSUPPORTED_FEATURE);
          }
  
          if (controlChannel.isIPv6()) {
              throw new ServerException(ServerException.UNSUPPORTED_FEATURE,
                                        "Cannot use GridFTP2 with IP 6");
          }
      }
docs: Throws ServerException if GFD.47 GETPUT is not supported or
  cannot be used.