Returns the optionset that matches given name.
string $name: The optionset name to be found.
array The requested optonset.
public function getOptionSet($name) {
/** @var \Drupal\slick\Entity\Slick $entity */
$entity = $this->slickManager
->entityLoad($name, 'slick');
return $entity ? $entity
->getSettings() : [];
}