@Override
  public synchronized Map<String, UUID> selectDigest(String keyPrefix, Predicate<String> keyFilter) {
    final Map<String, UUID> result = new TreeMap<>();
    digests.forEach((name, uuid) -> {
      if (name.startsWith(keyPrefix) && (keyFilter == null || keyFilter.test(name))) {
        result.put(name, uuid);
      }
    });
    return result.isEmpty() ? Collections.emptyMap() : result;
  }
The digests for the stored maps.
standalone-metastore/metastore-common/src/test/java/org/apache/hadoop/hive/metastore/properties/TransientPropertyStore.java