List<ReplicaId> getNextReplicaToHydrate(DiskId diskId, int numberOfReplicasOnDisk) {
    List<ReplicaId> replicaIds = prioritizationManager.getPartitionListForDisk(diskId, numberOfReplicasOnDisk);
    if (replicaIds == null) {
      return new ArrayList<>();
    }
    return replicaIds;
  }
Find the replicas that are starved for hydration. Return a list of Replicas
which are stuck in hydration for more than the configured values.
@return the list of {@link ReplicaId} that are starved for hydration.
ambry-file-transfer/src/main/java/com/github/ambry/filetransfer/FileCopyBasedReplicationSchedulerImpl.java