Description

thunderhook

opened on Jul 26, 2025

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The following mapper:

import org.mapstruct.Mapper;

class Override {}

class OverrideDto {}

class Car {
    public Override override;
}
class CarDto {
    public OverrideDto override;
}

@Mapper
interface Issue3904Mapper {
    CarDto map(Car car);
    OverrideDto map(Override override);
}

generates:

import javax.annotation.processing.Generated;

@Generated(
    value = "org.mapstruct.ap.MappingProcessor",
    date = "2025-07-26T10:41:47+0200",
    comments = "version: 1.6.0, compiler: javac, environment: Java 21.0.1 (Oracle Corporation)"
)
class Issue3904MapperImpl implements Issue3904Mapper {

    @Override
    public CarDto map(Car car) {
        if ( car == null ) {
            return null;
        }

        CarDto carDto = new CarDto();

        carDto.override = map( car.override );

        return carDto;
    }

    @Override
    public OverrideDto map(Override override) { // Incompatible types
        if ( override == null ) {
            return null;
        }

        OverrideDto overrideDto = new OverrideDto();

        return overrideDto;
    }
}

Override needs to get a fully qualified name, which it currently does not.
Interesting note: I also tried this with Generated (which could also clash) but this got a qully qualified name.

Another option would be to write @java.lang.Override.

Discussed in #3904

^{Originally posted by trico-tillster July 23, 2025}
I've 1 object to be mapped to another, if one of them contains a object called Override compiler fails.
This happens because generated code adds the @Override annotation to the implementation method, and compiler gets confused with the import class.
I've tried to search for a config to manipulate the generated annotation, something like updating it to @java.lang.Override, but I was not able.
I'm also not able to change the model Override class name to other, because this is a generated code from an external json schema.
Thought it would be helpful to mention this here.
Any clues how to solve this?

Reacted by Luís Tiago Barreto Rico

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1. thunderhook

   added the

   Bug

   issue type on Jul 26, 2025
2. thunderhook commented on Jul 26, 2025

   

   thunderhook

   on Jul 26, 2025

   ContributorAuthor

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   I just had a quick look. Even when we change it to a fully qualified name, there is an error:

       @Override // <-- Annotation type expected
       public OverrideDto map(example.package.Override override) {
           if ( override == null ) {
               return null;
           }
   
           OverrideDto overrideDto = new OverrideDto();
   
           return overrideDto;
       }

   Even if it is not imported via import it shows Annotation type expected.

   So to fix this, we would need to declare @java.lang.Override instead of @Override. Adding this by default might cause some issues with some code quality tools, but I'm not 100% sure.
3. filiphr

   added this to the 1.7.0 milestone on Jul 27, 2025
4. filiphr commented on Jul 27, 2025

   

   filiphr

   on Jul 27, 2025

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   I am not sure that I am following @thunderhook. Can you provide the entire class?

   If the example.package.Override is not in the import statements, then the code you shared should compile. I do not see a reason why it wouldn't compile?
5. thunderhook commented on Jul 28, 2025

   

   thunderhook

   on Jul 28, 2025

   ContributorAuthor

   More actions

   I'm not sure myself why Java behaves like that. I stumbled accross this while trying to fix it in a unit test. Just copy those classes to one of your projects (with the given packages) and have a look:

   package org.example._3904.inner;
   
   public class Override {
       public String name;
   }

   package org.example._3904.inner;
   
   public class OverrideDto {
       public String name;
   }

   package org.example._3904;
   
   import org.example._3904.inner.Override;
   import org.example._3904.inner.OverrideDto;
   import org.mapstruct.Mapper;
   
   @Mapper
   interface Issue3904Mapper {
       OverrideDto map(Override override);
   }

   package org.example._3904;
   
   import javax.annotation.processing.Generated;
   import org.example._3904.inner.Override;
   import org.example._3904.inner.OverrideDto;
   
   @Generated(
       value = "org.mapstruct.ap.MappingProcessor",
       date = "2025-07-28T07:37:57+0200",
       comments = "version: 1.6.3, compiler: javac, environment: Java 21.0.1 (Oracle Corporation)"
   )
   class Issue3904MapperImpl implements Issue3904Mapper {
   
       @Override // <- Annotation type expected
       public OverrideDto map(Override override) {
           if ( override == null ) {
               return null;
           }
   
           OverrideDto overrideDto = new OverrideDto();
   
           overrideDto.name = override.name;
   
           return overrideDto;
       }
   }

   In the generated class you can play around with the imports and fully qualified names. The only way I found was to give the Override a FQN. Maybe you have a better idea.
6. filiphr commented on Jul 31, 2025

   

   filiphr

   on Jul 31, 2025

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   The reason why you need an FQN in your example is because import org.example._3904.inner.Override is imported. If instead if importing that, we ise an FQQ in the map method then it works properly.

   e.g.

   public OverrideDto map(org.example._3904.inner.Override override) {

   Reacted by Luís Tiago Barreto Rico
7. filiphr

   added 2 commits that reference this issue on Aug 29, 2025

   mapstruct#3905: Using custom class Override should compile

   22e9be0

   #3905: Using custom class Override should compile

   4e1720c
8. filiphr

   closed this as completedin #3922on Aug 30, 2025

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