DcInfo join() throws Exception {
    try {
      return initializationFuture.get();
    } catch (ExecutionException e) {
      throw Utils.extractFutureExceptionCause(e);
    }
  }
Wait for startup to either succeed or fail.
@return the {@link DcInfo} for the datacenter (a handle to the stateful objects related to the datacenter).
@throws Exception if startup of the datacenter fails.
ambry-clustermap/src/main/java/com/github/ambry/clustermap/HelixDatacenterInitializer.java