@Override
  public Map<TimelineAppMetricCacheKey, TimelineMetricsCacheValue> loadAll(Iterable<? extends TimelineAppMetricCacheKey> keys) throws BulkCacheLoadingException, Exception {
//    no need to implement.
    return null;
  }
Time shift by a constant taking into account Epoch vs millis
ambari-server/src/main/java/org/apache/ambari/server/controller/metrics/timeline/cache/TimelineMetricCacheEntryFactory.java