Avoid extra call to KeyProvider::getMetadata()

    @Override
    public int comparePathKeyStrength(Path path1, Path path2) throws IOException {
      EncryptionZone zone1, zone2;

      zone1 = hdfsAdmin.getEncryptionZoneForPath(path1);
      zone2 = hdfsAdmin.getEncryptionZoneForPath(path2);

      if (zone1 == null && zone2 == null) {
        return 0;
      } else if (zone1 == null) {
        return -1;
      } else if (zone2 == null) {
        return 1;
      }

      return compareKeyStrength(zone1.getKeyName(), zone2.getKeyName());
    }

    private int compareKeyStrength(String keyname1, String keyname2) throws IOException {
      KeyProvider.Metadata meta1, meta2;

      if (keyProvider == null) {
        throw new IOException("HDFS security key provider is not configured on your server.");
      }

      meta1 = keyProvider.getMetadata(keyname1);
      meta2 = keyProvider.getMetadata(keyname2);

      if (meta1.getBitLength() < meta2.getBitLength()) {
        return -1;
      } else if (meta1.getBitLength() == meta2.getBitLength()) {
        return 0;
      } else {
        return 1;
      }
    }
  }