List<String> examineUnreachablePartitions(List<PartitionId> unreachablePartitions) {
    List<String> unreachableStores = new ArrayList<>();
    for (PartitionId partition : unreachablePartitions) {
      if (partitionToReplicaMap.containsKey(partition)) {
        unreachableStores.add(partition.toPathString());
      } else {
        logger.info("Removing partition {} from unreachable list because it is no longer in StatsManager",
            partition.toPathString());
      }
    }
    return unreachableStores;
  }
Re-examine the unreachable partitions to preclude those already removed from StatsManager.
@param unreachablePartitions a list of unreachable partitions generated during stats aggregation.
@return a list of stores which are unreachable and still present in StatsManager.
ambry-server/src/main/java/com/github/ambry/server/StatsManager.java