@Test
  @Ignore
  public void failedDueToOfflineReplicaTest() {
    failedDueToOfflineReplicaTest(RouterOperation.TtlUpdateOperation);
    failedDueToOfflineReplicaTest(RouterOperation.DeleteOperation);
  }
Test cases where some replicas have changed their state in the middle of constructing operation tracker. The code
should be able to get correct number of replicas even with concurrent state transition. The most common case is
replica changes from OFFLINE to BOOTSTRAP/STANDBY while the replica pool is being populated in the tracker.
ambry-router/src/test/java/com/github/ambry/router/OperationTrackerTest.java