Method appendButton

/**
 * Append a button to toolbar.
 *
 * @param   ToolbarButton  $button  The button instance.
 * @param   array          $args    The more arguments.
 *
 * @return  ToolbarButton|boolean  Return button instance to help chaining configure. If using legacy arguments
 *                                 returns true
 *
 * @since   1.5
 */
public function appendButton($button, ...$args)
{
    if ($button instanceof ToolbarButton) {
        $button->setParent($this);
        $this->_bar[] = $button;
        return $button;
    }
    // B/C
    array_unshift($args, $button);
    $this->_bar[] = $args;
    @trigger_error(sprintf('%s::appendButton() should only accept %s instance in Joomla 5.0.', static::class, ToolbarButton::class), E_USER_DEPRECATED);
    return true;
}