modules.addAll(moduleRegistry.getModule(name).getAllRequiredModules());
        }
        return modules;
    }

    private Set<Module> allRequiredModulesOfOptional(String moduleName) {
        Module optionalModule = moduleRegistry.findModule(moduleName);
        if (optionalModule != null) {
            return optionalModule.getAllRequiredModules();
        }
        return emptySet();
    }

     */
    Set<Module> getRequiredModules();

    /**
     * Returns the transitive closure of all modules required by this module, including the module itself.
     */
    Set<Module> getAllRequiredModules();

    /**
     * Returns the implementation + runtime classpath of the transitive closure of all modules required by this module, including the module itself.
     */
    ClassPath getAllRequiredModulesClasspath();

        @Override
        public Set<Module> getAllRequiredModules() {
            Set<Module> modules = new LinkedHashSet<>();
            collectRequiredModules(modules);
            return modules;
        }

        @Override
        public ClassPath getAllRequiredModulesClasspath() {
            ClassPath classPath = ClassPath.EMPTY;
            for (Module module : getAllRequiredModules()) {