Provide link to file option
Overrides FieldPluginBase::buildOptionsForm
public function buildOptionsForm(&$form, &$form_state) {
$form['link_to_file'] = array(
'#title' => t('Link this field to download the file'),
'#description' => t("Enable to override this field's links."),
'#type' => 'checkbox',
'#default_value' => !empty($this->options['link_to_file']),
);
parent::buildOptionsForm($form, $form_state);
}