Method prepareOptions

/**
 * Prepare options for this button.
 *
 * @param   array  $options  The options about this button.
 *
 * @return  void
 *
 * @since  4.0.0
 */
protected function prepareOptions(array &$options)
{
    parent::prepareOptions($options);
    if (empty($options['is_child'])) {
        $class = $this->fetchButtonClass($this->getName());
        $options['btnClass'] = $options['button_class'] = $options['button_class'] ?? $class;
    }
    $options['onclick'] = $options['onclick'] ?? $this->_getCommand();
}