Respect only explicit mappings but fail on unmapped source fields #3574

class MyDto {
  private JsonNullable<String> firstname;
  private JsonNullable<String> surname
}

@Mapper(nullValuePropertyMappingStrategy = NullValuePropertyMappingStrategy.IGNORE,
        unmappedSourcePolicy = ReportingPolicy.ERROR)
interface MyPartialUpdateMapper {

  @Mapping(source = "firstname", target = "firstname", conditionExpression = "java(updatedContent.getFirstname().isPresent())")
  @BeanMapping(ignoreByDefault = true)
  void updateMyDomainObject(@MappingTarget MyDomainObject domain, MyDto updatedContent);

  default <T> T fromJsonNullable(JsonNullable<T> nullableValue) {
      if(nullableValue.isPresent()) {
          return nullableValue.get();
      }
      return null;
  }
}