code: public static boolean parityExists(FileStatus src, Codec codec,
        Configuration conf) throws IOException {
      return ParityFilePair.getParityFile(codec, src, conf) != null;
    }
docs: Return whether if parity file of the source file exists or not
  
  @param src     The FileStatus of the source file.
  @param codec   The Codec of the parity to check
  @param conf
  @return
  @throws IOException