code: boolean unprotectedHardLinkTo(String src, String dst, long timestamp)
    throws QuotaExceededException, FileNotFoundException {
      return unprotectedHardLinkTo(src, null, null, null, dst, null, null, null, timestamp);
    }
docs: hard link the dst path to the src path
  
  @param src source path
  @param dst destination path
  @param timestamp The modification timestamp for the dst's parent directory
  @return true if the hardLink succeeds; false otherwise
  @throws QuotaExceededException if the operation violates any quota limit
  @throws FileNotFoundException