public final void write(boolean shuttingDown) throws IOException, ReplicationException {
    for (String mountPath : partitionGroupedByMountPath.keySet()) {
      if (!mountPathsToSkip.contains(mountPath)) {
        write(mountPath, shuttingDown);
      }
    }
  }
Iterates through each mount path and persists all the replica tokens for the partitions on the mount
path to a file. The file is saved on the corresponding mount path.
@param shuttingDown indicates whether this is being called as part of shut down.
ambry-replication/src/main/java/com/github/ambry/replication/ReplicaTokenPersistor.java