Default options form that provides the label widget that all fields should have.
Overrides FieldPluginBase::buildOptionsForm
public function buildOptionsForm(&$form, &$form_state) {
$form['link_to_user'] = array(
'#title' => t("Link this field to its user or an author's homepage"),
'#type' => 'checkbox',
'#default_value' => $this->options['link_to_user'],
);
parent::buildOptionsForm($form, $form_state);
}