Mapstruct is not generating implementation for one of my mapper interfaces. Is there a way to know the reason? - mapstruct

Question

I am using mapstruct to map from/to domain objects to DTO
I have more than 20 mappers that are properly being generated.
One of my mappers is no longer being generated, but compilation is successful.
I use maven and i turned on showWarnings flag in the maven-compiler-plugin configuration, however i see no warnings regarding that specific mapper (I do see warnings for other mappers).
Is there a way to get some information from the annotation processor regarding mappers that are not being generated?
My mapper interface (with name changes):
#Mapper
public interface PersonMapper {
PersonMapper INSTANCE = Mappers.getMapper(PersonMapper.class);
PersonDTO map(Person entity);
Person map(PersonDTO dto);
}
My Maven configuration:
...
<dependency>
<groupId>org.mapstruct</groupId>
<artifactId>mapstruct-jdk8</artifactId>
<version>1.3.0.Final</version>
</dependency>
...
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.5.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
<annotationProcessorPaths>
...
<path>
<groupId>org.mapstruct</groupId>
<artifactId>mapstruct-processor</artifactId>
<version>1.3.0.Final</version>
</path>
</annotationProcessorPaths>
<showWarnings>true</showWarnings>
</configuration>
</plugin>

Answer 1

You can do basic tracing (verbose mode) in the upcoming version of MapStruct. Checkout the documentation. You can try to use the latest MapStruct master in your project and see if it gives info on why this is not working.

Answer 2

For me it was a dependency issue.
My Projet A, had a dependency to another jar B, which contained the object from my mapper method.
That dependency B had a dependency C offering mapstruct mapper for many of the attribut of the object.
Somehow in my project A i was overriding explicitly the version of dependency C to an older version.
So it means that some of the Obj attribute from current B version where not matching with the older C mapper.
Mapstruct said nothing, just stopped generating the impl.
Not sure if this is very clear ... But check your dependencies.