private List<RemoteReplicaGroup> getInflightGroups() {
      List<RemoteReplicaGroup> allRemoteReplicaGroups = new ArrayList<>();
      dataNodeTrackers.forEach(dataNodeTracker -> {
        allRemoteReplicaGroups.addAll(dataNodeTracker.getInflightRemoteReplicaGroups());
      });
      return allRemoteReplicaGroups;
    }
@return Iterates over all data nodes and returns list of all remote replica groups
that are getting tracked
ambry-replication/src/main/java/com/github/ambry/replication/ReplicaThread.java