Guice -如何让多个模块贡献一件事？

public interface Something {
    void doSomething();
}

public class ModuleA extends AbstractModule {
    @Override
    protected void configure() {
        bind(Something.class).to(SomethingImplA.class);
    }
}

public class ModuleB extends AbstractModule {
    @Override
    protected void configure() {
        bind(Something.class).to(SomethingImplB.class);
    }
}

public class MainModule extends AbstractModule {
    @Override
    protected void configure() {
        install(new ModuleA());
        install(new ModuleB());
    }
}

public class MyApp {
    @Inject
    private Something something;

    public void run() {
        something.doSomething();
    }
}