code: public static HdfsStatsKey parseHdfsStatsKey(byte[][] keyComponents) {
      return new HdfsStatsKey(new QualifiedPathKey(
          // cluster:
          (keyComponents.length > 1 ? Bytes.toString(keyComponents[1]) : null),
          // path:
          (keyComponents.length > 2 ? Bytes.toString(keyComponents[2]) : null),
          // namespace:
          (keyComponents.length > 3 ? Bytes.toString(keyComponents[3]) : null)),
          // encodedRunId:
          (keyComponents.length > 0 ? Long.parseLong(Bytes.toString(keyComponents[0])) : null));
    }
docs: Constructs a HdfsStatsKey instance from the
  individual byte encoded key components.
  
  @param keyComponents
  as split on Separator '!'
  @return a HdfsStatsKey instance containing the decoded components