Provide a form to edit options for this plugin.
Overrides StylePluginBase::buildOptionsForm
public function buildOptionsForm(&$form, &$form_state) {
parent::buildOptionsForm($form, $form_state);
$form['formats'] = array(
'#type' => 'checkboxes',
'#title' => t('Accepted request formats'),
'#description' => t('Request formats that will be allowed in responses. If none are selected all formats will be allowed.'),
'#options' => drupal_map_assoc($this->formats),
'#default_value' => $this->options['formats'],
);
}