MongoDB.Bson.Serialization.Serializers.BsonDocumentSerializer.GetDocumentId C# (CSharp) Метод

        public bool GetDocumentId(
            object document,
            out object id,
            out Type idNominalType,
            out IIdGenerator idGenerator)
        {
            var bsonDocument = (BsonDocument)document;

            BsonElement idElement;
            if (bsonDocument.TryGetElement("_id", out idElement))
            {
                id = idElement.Value;
                idGenerator = BsonSerializer.LookupIdGenerator(id.GetType());

                if (idGenerator == null)
                {
                    var idBinaryData = id as BsonBinaryData;
                    if (idBinaryData != null && (idBinaryData.SubType == BsonBinarySubType.UuidLegacy || idBinaryData.SubType == BsonBinarySubType.UuidStandard))
                    {
                        idGenerator = BsonBinaryDataGuidGenerator.GetInstance(idBinaryData.GuidRepresentation);
                    }
                }
            }
            else
            {
                id = null;
                idGenerator = BsonObjectIdGenerator.Instance;
            }

            idNominalType = typeof(BsonValue);
            return true;
        }