lombok-trait-2.java

@Trait(impl=Counter.class)
interface CounterTrait {
  public int countup();
}

class Counter implements CounterTrait {
  private int value = 0;
  public int countup(){
    value++;
    return value;
  }
  protected int countdown(){
    value--;
    return value;
  }
}

@UseTrait
class Foo implements CounterTrait {
  public int countup();
}

-----------

class Foo implements CounterTrait {
  private static class CounterTraitDelegatee extends Counter {
    protected int countdown(){
      super.countdown();
    }
  }
  private CounterTraitDelegatee __counter_trait_delegatee__ = new CounterTraitDelegatee() {};
  public int countup(){
    return __counter_trait_delegatee__.countup();
  }
  protected int countdown(){
    return __counter_trait_delegatee__.countdown();
  }
}

lombok-trait.java

@Trait
abstract class Counter {
  private int value = 0;
  public int countup(){
    value++;
    return value;
  }
  protected int countdown(){
    value--;
    return value;
  }
}

@UseTrait
class Foo implements CounterTrait {
  
}

-----------

@GeneratedTrait(base=Counter.class)
interface CounterTrait {
  public int countup();
}

class Foo implements CounterTrait {
  private static class CounterTraitDelegatee extends Counter {
    protected int countdown(){
      super.countdown();
    }
  }
  private CounterTraitDelegatee __counter_trait_delegatee__ = new CounterTraitDelegatee() {};
  public int countup(){
    return __counter_trait_delegatee__.countup();
  }
  protected int countdown(){
    return __counter_trait_delegatee__.countdown();
  }
}