public void SerializeProperty(
     BsonWriter bsonWriter,
     object obj,
     BsonPropertyMap propertyMap
 )
 {
     var employee = (Employee) obj;
     bsonWriter.WriteString(propertyMap.ElementName, employee.DateOfBirth.ToString("yyyy-MM-dd"));
 }
 public void DeserializeProperty(
     BsonReader bsonReader,
     object obj,
     BsonPropertyMap propertyMap
 )
 {
     var employee = (Employee) obj;
     employee.DateOfBirth = DateTime.Parse(bsonReader.ReadString(propertyMap.ElementName));
 }