pass-thru.java

class Controller {
    ApplicationService service;

    void method(String potentialNull) {
        // stuff
        if (potentialNull == null) {
            service.method();
        } else {
            service.method(potentialNull);
        }
        // stuff
    }
}

class ApplicationService {
    DomainService service;

    void method() {
        // stuff
        service.method();
        // stuff
    }

    void method(String argument) {
        // stuff
        service.method(argument);
        // stuff
    }
}

class DomainService {
    void method() {
        // stuff
        DomainObject object = ...
        object.method();
        // stuff
    }

    void method(String argument) {
        // stuff
        DomainObject object = ...
        object.method(argument);
        // stuff
    }
}

class DomainObject {
    void method() {
        method("reasonable default");
    }

    void method(String argument) {
        // stuff
    }
}