code: protected void loadModules(String sourceDir, Collection<String> moduleNames) {
          ModuleFinder finder = ModuleFinder.of(Paths.get(sourceDir));
          ClassLoader scl = ClassLoader.getSystemClassLoader();
          ModuleLayer parent = ModuleLayer.boot();
          Configuration cf = parent.configuration().resolve(finder, ModuleFinder.of(), moduleNames);
          layer = parent.defineModulesWithOneLoader(cf, scl);
      }
docs: Load all the modules that were configured into the main class loader, we don't want any additional class
  loaders, we just want to load the classes in.
  @param sourceDir the directory where the modules exist
  @param moduleNames the names of all the modules to load