public static ConcurrentDictionary <int, ConcurrentDictionary <byte, byte?> > ReadNullableByteFieldDictionary(this ITypeReader serializer)
        {
            var result = new ConcurrentDictionary <int, ConcurrentDictionary <byte, byte?> >();

            try
            {
                var cnt = serializer.ReadInt();
                for (int i = 0; i < cnt; i++)
                {
                    var key    = serializer.ReadInt();
                    var val    = new ConcurrentDictionary <byte, byte?>();
                    var subCnt = serializer.ReadInt();
                    for (int j = 0; j < subCnt; j++)
                    {
                        var subKey   = serializer.ReadByte();
                        var subValue = serializer.ReadNullableByte();
                        val.TryAdd(subKey, subValue);
                    }
                    result.TryAdd(key, val);
                }
            }
            catch (Exception e)
            {
                throw new Exception($"Error serializing ConcurrentDictionary<int, ConcurrentDictionary<ChangeFieldIndexes, byte?>>: {e}");
            }

            return(result);
        }