code: public static FsPermission getUMask(Configuration conf) {
      int umask = DEFAULT_UMASK;
      
      // To ensure backward compatibility first use the deprecated key.
      // If the deprecated key is not present then check for the new key
      if(conf != null) {
        String confUmask = conf.get(UMASK_LABEL);
        if(confUmask != null) {
          umask = new UmaskParser(confUmask).getUMask();
        }
        
        int oldUmask = conf.getInt(DEPRECATED_UMASK_LABEL, Integer.MIN_VALUE);
        if(oldUmask != Integer.MIN_VALUE) { // Property was set with old key
          if (umask != oldUmask) {
            LOG.warn(DEPRECATED_UMASK_LABEL
                + " configuration key is deprecated. " + "Convert to "
                + UMASK_LABEL + ", using octal or symbolic umask "
                + "specifications.");
            // Old and new umask values do not match - Use old umask
            umask = oldUmask;
          }
        }
      }
      
      return new FsPermission((short)umask);
    }
docs: Get the user file creation mask (umask)