public void DeserializeProperty(
     BsonReader bsonReader,
     object obj,
     BsonPropertyMap propertyMap
 )
 {
     var bsonType = bsonReader.PeekBsonType();
     BsonMinKey value;
     if (bsonType == BsonType.Null) {
         bsonReader.ReadNull(propertyMap.ElementName);
         value = null;
     } else {
         bsonReader.ReadMinKey(propertyMap.ElementName);
         value = Bson.MinKey;
     }
     propertyMap.Setter(obj, value);
 }