code: private HadoopVersion getHadoopVersionFromResult(final JobHistoryKeys key,
        final NavigableMap<byte[], byte[]> infoValues) {
      byte[] value = infoValues.get(JobHistoryKeys.KEYS_TO_BYTES.get(key));
      if (value != null) {
        String hv = Bytes.toString(value);
        // could throw an NPE or IllegalArgumentException
        return HadoopVersion.valueOf(hv);
      } else {
        // default is hadoop 1
        return HadoopVersion.ONE;
      }
    }
docs: return an enum value from the NavigableMap for hadoop version
  @param key
  @param infoValues
  @return value as a enum or default of hadoop ONE