Akka.Cluster.Reachability.Cache.Cache C# (CSharp) Метод

            public Cache(ImmutableList<Record> records)
            {
                if (records.IsEmpty)
                {
                    _observerRowsMap = ImmutableDictionary.Create<UniqueAddress, ImmutableDictionary<UniqueAddress, Record>>();
                    _allTerminated = ImmutableHashSet.Create<UniqueAddress>();
                    _allUnreachable = ImmutableHashSet.Create<UniqueAddress>();
                }
                else
                {
                    var mapBuilder = new Dictionary<UniqueAddress, ImmutableDictionary<UniqueAddress, Record>>();
                    var terminatedBuilder = ImmutableHashSet.CreateBuilder<UniqueAddress>();
                    var unreachableBuilder = ImmutableHashSet.CreateBuilder<UniqueAddress>();

                    foreach (var r in records)
                    {
                        ImmutableDictionary<UniqueAddress, Record> m;
                        if(mapBuilder.TryGetValue(r.Observer, out m))
                        {
                            m = m.SetItem(r.Subject, r);                            
                        }
                        else
                        {
                            //TODO: Other collections take items for Create. Create unnecessary array here
                            m = ImmutableDictionary.CreateRange(new[] { new KeyValuePair<UniqueAddress, Record>(r.Subject, r) });
                        }
                        mapBuilder.AddOrSet(r.Observer, m);

                        if (r.Status == ReachabilityStatus.Unreachable) unreachableBuilder.Add(r.Subject);
                        else if (r.Status == ReachabilityStatus.Terminated) terminatedBuilder.Add(r.Subject);
                    }

                    _observerRowsMap = ImmutableDictionary.CreateRange(mapBuilder);
                    _allTerminated = terminatedBuilder.ToImmutable();
                    _allUnreachable = unreachableBuilder.ToImmutable().Except(AllTerminated);
                }

                _allUnreachableOrTerminated = _allTerminated.IsEmpty
                    ? AllUnreachable
                    : AllUnreachable.Union(AllTerminated);
            }
        }