@Override
    public List<LogInfo> getLogSegmentMetadataFiles(boolean includeActiveLogSegment) {
      throw new IllegalStateException("Not implemented");
    }
Mocked {@link Store} that is intended to return a predefined {@link StoreStats} when getStoreStats is called.
ambry-server/src/test/java/com/github/ambry/server/StatsManagerTest.java