@Override
    protected void addStageInformation(@Nonnull final SessionData data, Element command) {
        final Locale preferredLocale = SessionManager.getInstance().getLocaleForSession(data.getOwner());

        DataForm form = new DataForm(DataForm.Type.form);
        form.setTitle(LocaleUtils.getLocalizedString("commands.event.userdeleting.form.title", preferredLocale));
        form.addInstruction(LocaleUtils.getLocalizedString("commands.event.userdeleting.form.instruction", preferredLocale));

        FormField field = form.addField();
        field.setType(FormField.Type.hidden);
        field.setVariable("FORM_TYPE");
        field.addValue("http://jabber.org/protocol/admin");

        field = form.addField();
        field.setType(FormField.Type.text_single);
        field.setLabel(LocaleUtils.getLocalizedString("commands.event.userdeleting.form.field.username.label", preferredLocale));
        field.setVariable("username");
        field.setRequired(true);

        // Add the form to the command
        command.add(form.getElement());
    }
Notifies the deletion of a user. It can be used by user providers to notify Openfire of the
deletion of a user.

@author Gabriel Guarincerri
xmppserver/src/main/java/org/jivesoftware/openfire/commands/event/UserDeleting.java