void validateIfPzManagerIsRunningOrThrowException(ReplicaId replicaId){
    if(!isRunning){
      logger.error("Partition {} failed adding to prioritization Manager", replicaId.getReplicaPath());
      throw new StateTransitionException("Partition " + replicaId.getReplicaPath() + " failed adding to "
          + "prioritization Manager", PrioritizationManagerRunningFailure);
    }
  }
The FCFSPrioritizationManager is a First-Come-First-Serve implementation of the PrioritizationManager.
ambry-prioritization/src/main/java/com/github/ambry/replica/prioritization/FCFSPrioritizationManager.java