@Override
  public boolean renameProperties(String mapKey, String newKey) {
    synchronized (this) {
      // target is unencumbered
      if (!maps.containsKey(newKey)) {
        PropertyMap map = maps.remove(mapKey);
        // we got a source
        if (map != null) {
          maps.put(newKey, map);
          return true;
        }
      }
      return false;
    }
  }
A property map store using a pull-thru cache.
<p>
Before a map is returned, a check against the stored corresponding digest is performed to avoid
using stale data.
</p>
standalone-metastore/metastore-common/src/main/java/org/apache/hadoop/hive/metastore/properties/CachingPropertyStore.java