[FEATURE] covariant override of chained setters in subclass

[jhannes]

When I create type hierarchies of data-types with chainable setters, setting a property on the superclass will return the type of the superclass. This means that I cannot subsequently call methods on the subclass. As Java supports covariant return types, this can be fixed with a simple matter of code generation

Describe the feature

Considering the following classes

@Data
public class Pet {
    private String name;
}

@Data
public class Dog extends Pet {
   private String breed;
}

Given lombok.accessor.chain=true , the following compiles:

new Dog().setBreed("Labradoodle").setName("Fido");

But this does not compile, because setName has return type Pet:

new Dog().setName("Fido").setBreed("Labradoodle");

Either by default or with a flag, the following code could be generated:

public class Pet {
    private String name;
    public String getName() {
         return this.name;
    }
    public Pet setName(String name) {
         this.name = name;
         return this;
    }
}

public class Dog extends Pet {
    private String breed;
    public String getBreed() {
         return this.breed;
    }
    public Dog setBreed(String breed) {
         this.breed = breed;
    }

    /* THIS IS THE PROPOSED CHANGE; covariant override of chained setter */
    @Override
    public Dog setName(String name) {
         super.setName(name);
         return this;
    }
}

Describe the target audience

This is useful for Data classes in hierarchies with chaining setters.