module module-a {
    exports com.mod-a;
}

module module-c {
    requires module-a;
    provides com.mod-a.Service with com.mod-c.ServiceImpl;
}

module module-b {
    required module-a;
    requires java.management;
    requires slf4j.api;
    uses com.mod-a.Service;
}

ModuleFinder finder = ModuleFinder.of(moduleCPath);
ModuleLayer parent = ModuleLayer.boot();
Configuration cf = parent.configuration().resolve(finder, ModuleFinder.of(), Set.of("module-c"));
ClassLoader scl = ClassLoader.getSystemClassLoader();
ModuleLayer layer = parent.defineModulesWithOneLoader(cf, scl);
//the following line prints "module-c"
layer.modules().stream().map(Module::getName).forEach(System.out::println);

Iterable<Service> it = ServiceLoader.load(Service.class);
System.out.println("LINE 1");
for (Service service : it) {
     System.out.println("Service was called");
     service.doIt();
}
System.out.println("LINE 2");

LINE 1
LINE 2