Improve Lombok integration documentation #3374

Expected behavior

Assuming the following code and configuration below, I expect the compilation to succeed and the mapper to generate something like this:

public Foo.CarDto toDto(Foo.Car car) {
    if (car == null) {
        return null;
    } else {
        Foo.CarDto carDto = new Foo.CarDto();
        carDto.setEWhatever2(car.getEWhatever1());
        return carDto;
    }
}

Actual behavior

Compilation fails and no implementation is generated.

java: No property named "eWhatever1" exists in source parameter(s). Did you mean "EWhatever1"?

Steps to reproduce the problem

• Java 17
• MapStruct 1.5.3.Final
• Lombok 1.18.22
• Lombok Mapstruct Binding 0.2.0

@Mapper
public interface BadMapper {

    @Mapping(target = "eWhatever2", source = "eWhatever1")
    CarDto toDto(Car car);
}

@Data
public class Car {

    private String eWhatever1;
}

@Data
public class CarDto {

    private String eWhatever2;
}

It is important the 1st letter of the variable is lowercase and the 2nd one is uppercase.

• Ewhatever interestingly produces a similar error.
• eWhatever doesn't work.
• ewHatever is ok.
• ewhatever is ok.

MapStruct Version

MapStruct 1.5.3.Final