Internationalization version selector imputprompt

I am following this for internationalization document in magnolia cms 5.7.

I need to internationalize the version selector input prompt in the pagebar but cannot find the key for this value.

import com.vaadin.v7.ui.ComboBox;
private ComboBox versionSelector = new ComboBox();
    private Listener listener;



    public VersionSelectorViewImpl() {
        construct();
    }

    private void construct() {
        versionSelector.setVisible(false);
        versionSelector.setImmediate(true);
        versionSelector.setNullSelectionAllowed(false);
        versionSelector.setTextInputAllowed(false);
        versionSelector.setInputPrompt("Select a version"); //***this is the key I need ***
        versionSelector.addStyleName("version-selector");
        versionSelector.setSizeFull();
        

I was able to solve this by injecting SimpleTranslator in the constructor:

            private final SimpleTranslator i18n;
        
            @Inject
            public VersionSelectorViewImpl(SimpleTranslator i18n){
                this.i18n = i18n;
                construct();
            }
        
        
            private void construct() {
                String inputPrompt = i18n.translate("module.pagebar.selectVersion");
                
                versionSelector.setInputPrompt(inputPrompt);
                ...
            }

and then passing the key value found in the message bundle file for each language respectively.

An example is also found here info.magnolia.contacts.app.field.component.ContactPreviewComponent.