public interface BaseService<T> {

    void setSomething(T param);

    T getSomething();

}

public abstract class BaseServiceImpl<T> implements BaseService<T> {

    @Override

    public void setSomething(T param) {

    }

    @Override

    public T getSomething() {

        return null;

    }

}

public interface SpecialService extends BaseService<String> {

    @Override

    // for declaring some special annotations

    void setSomething(String param);

    @Override

    String getSomething();

}

@SomeInterceptorBinding

public class ManagedSpecialServiceImpl extends BaseServiceImpl<String> implements SpecialService {

}

@Stateless

@Local(SpecialService.class)

@SomeInterceptorBinding

public class EJBSpecialServiceImpl extends BaseServiceImpl<String> implements SpecialService {

}