@Override
 public Settings additionalSettings() {
   return Settings.builder()
       .put("foo.bar", "1")
       .put(
           IndexModule.INDEX_STORE_TYPE_SETTING.getKey(),
           IndexModule.Type.MMAPFS.getSettingsKey())
       .build();
 }
 public void testAdditionalSettings() {
   Settings settings =
       Settings.builder()
           .put("path.home", createTempDir())
           .put("my.setting", "test")
           .put(
               IndexModule.INDEX_STORE_TYPE_SETTING.getKey(),
               IndexModule.Type.SIMPLEFS.getSettingsKey())
           .build();
   PluginsService service = newPluginsService(settings, AdditionalSettingsPlugin1.class);
   Settings newSettings = service.updatedSettings();
   assertEquals("test", newSettings.get("my.setting")); // previous settings still exist
   assertEquals("1", newSettings.get("foo.bar")); // added setting exists
   assertEquals(
       IndexModule.Type.SIMPLEFS.getSettingsKey(),
       newSettings.get(
           IndexModule.INDEX_STORE_TYPE_SETTING
               .getKey())); // does not override pre existing settings
 }