func (kv *ShardKV) getReconfigureEntry(nextConfig shardmaster.Config) (Op, bool) {
	entry := Op{}
	entry.Command = "reconfigure"
	entry.Config = nextConfig
	for i := 0; i < shardmaster.NShards; i++ {
		entry.Data[i] = make(map[string]string)
	}
	entry.Ack = make(map[int64]int64)
	ok := true

	var ackMu sync.Mutex
	var wg sync.WaitGroup

	transferShards := kv.getShardsToTransfer(nextConfig)
	for gid, shardIds := range transferShards {
		wg.Add(1)

		go func(gid int, args TransferShardArgs, reply TransferShardReply) {
			defer wg.Done()

			if kv.sendTransferShard(gid, &args, &reply) {
				ackMu.Lock()
				// copy only shards requested from that replica group to reconfigure args
				for _, shardId := range args.ShardIds {
					shardData := reply.Data[shardId]
					for k, v := range shardData {
						entry.Data[shardId][k] = v
					}
				}
				// merge ack map from that replica group to reconfigure args
				for clientId := range reply.Ack {
					if _, ok := entry.Ack[clientId]; !ok || entry.Ack[clientId] < reply.Ack[clientId] {
						entry.Ack[clientId] = reply.Ack[clientId]
					}
				}
				ackMu.Unlock()
			} else {
				ok = false
			}
		}(gid, TransferShardArgs{Num: nextConfig.Num, ShardIds: shardIds}, TransferShardReply{})
	}
	wg.Wait()
	return entry, ok
}