presto-raptor-legacy/src/main/java/io/prestosql/plugin/raptor/legacy/storage/ShardRecoveryManager.java/MissingShardsQueue/submit
class MissingShardsQueue:        public ListenableFuture<?> submit(MissingShard shard)
                throws ExecutionException
        {
            return queuedMissingShards.get(shard);
        }