MongoDB.Bson.Serialization.Serializers.BsonValueCSharpNullSerializer.IsCSharpNullRepresentation C# (CSharp) Метод

        private bool IsCSharpNullRepresentation(BsonReader bsonReader)
        {
            var bookmark = bsonReader.GetBookmark();
            bsonReader.ReadStartDocument();
            var bsonType = bsonReader.ReadBsonType();
            if (bsonType == BsonType.Boolean)
            {
                var name = bsonReader.ReadName();
                if (name == "_csharpnull" || name == "$csharpnull")
                {
                    var value = bsonReader.ReadBoolean();
                    if (value)
                    {
                        bsonType = bsonReader.ReadBsonType();
                        if (bsonType == BsonType.EndOfDocument)
                        {
                            bsonReader.ReadEndDocument();
                            return true;
                        }
                    }
                }
            }

            bsonReader.ReturnToBookmark(bookmark);
            return false;
        }
    }