@Override
  public synchronized boolean renameProperties(String mapKey, String newKey) {
    if (!properties.containsKey(newKey)) {
      byte[] map = properties.remove(mapKey);
      if (map != null) {
        properties.put(newKey, map);
        UUID digest = digests.remove(mapKey);
        if (digest != null) {
          digests.put(newKey, digest);
        }
        return true;
      }
    }
    return false;
  }
The digests for the stored maps.
standalone-metastore/metastore-common/src/test/java/org/apache/hadoop/hive/metastore/properties/TransientPropertyStore.java