Overrides Drupal\views\Plugin\views\row\RowPluginBase::buildOptionsForm().
Overrides RowPluginBase::buildOptionsForm
public function buildOptionsForm(&$form, &$form_state) {
parent::buildOptionsForm($form, $form_state);
$form['test_option'] = array(
'#type' => 'textfield',
'#description' => t('This is a textfield for test_option.'),
'#default_value' => $this->options['test_option'],
);
}