private function buildCommitRequest()
{
$obj_request = (object) ['mutations' => []];
// Transaction at root level, so do not use applyTransaction()
if (null !== $this->str_next_transaction) {
$obj_request->transaction = $this->str_next_transaction;
$obj_request->mode = self::MODE_TRANSACTIONAL;
$this->str_next_transaction = null;
} else {
$obj_request->mode = self::MODE_NON_TRANSACTIONAL;
}
return $obj_request;
}