@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.admin.getlistonlineusers.form.title", preferredLocale));
        form.addInstruction(LocaleUtils.getLocalizedString("commands.admin.getlistonlineusers.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.list_single);
        field.setLabel(LocaleUtils.getLocalizedString("commands.global.operation.pagination.max_items", preferredLocale));
        field.setVariable("max_items");
        field.addOption("25", "25");
        field.addOption("50", "50");
        field.addOption("75", "75");
        field.addOption("100", "100");
        field.addOption("150", "150");
        field.addOption("200", "200");
        field.addOption(LocaleUtils.getLocalizedString("commands.global.operation.pagination.none", preferredLocale), "none");

        // Add the form to the command
        command.add(form.getElement());
    }
Command that allows to retrieve the number of registered users who are online at
any one moment. By "online user" is meant any user or account that currently has
an IM session that may or may not be available.

@author Guus der Kinderen, guus@goodbytes.nl
@see <a href="https://xmpp.org/extensions/xep-0133.html#get-online-users-list">XEP-0133 Service Administration: Get List of Online Users</a>
xmppserver/src/main/java/org/jivesoftware/openfire/commands/admin/GetListOnlineUsers.java