protected function getBranchItemsSelection($fields = null)
{
$fields = Tools::listToArray($fields);
if (!$fields) {
$fields = array_merge($fields, Tools::listToArray($this->getObjectDefinition()->getDefaultSelection()));
}
$fields = array_merge($fields, Tools::listToArray($this->getObjectDefinition()->getTreeLabel()));
$fields = array_merge($fields, Tools::listToArray($this->getObjectDefinition()->getTreeFields()));
$fields = array_merge($fields, Tools::listToArray($this->getObjectDefinition()->getTreeIcon()));
$fields = $this->applyDefaultSelection($fields);
return $fields;
}