code: public UnderFileSystemConfiguration createMountSpecificConf(Map<String, String> mountConf) {
      UnderFileSystemConfiguration ufsConf = new UnderFileSystemConfiguration(mProperties.copy());
      ufsConf.mProperties.merge(mountConf, Source.MOUNT_OPTION);
      ufsConf.mReadOnly = mReadOnly;
      ufsConf.mShared = mShared;
      return ufsConf;
    }
docs: Creates a new instance from the current configuration and adds in new properties.
  @param mountConf the mount specific configuration map
  @return the updated configuration object