public function buildOptionsForm(&$form, FormStateInterface $form_state) {
parent::buildOptionsForm($form, $form_state);
$options = array(
'' => t('- All -'),
);
$options += JobItem::getStates();
$form['state'] = array(
'#title' => t('Job item state'),
'#description' => t('Count only job items of a certain state.'),
'#type' => 'select',
'#options' => $options,
'#default_value' => $this->options['state'],
);
}