Sync/SyncStorage/SyncStorage.php
private function isValidOperation($operationType)
    {
        $operationType = strtoupper($operationType);

        return in_array(
            $operationType,
            [
                ActionTypes::CREATE,
                ActionTypes::UPDATE,
                ActionTypes::DELETE,
            ]
        );
    }
private function isValidOperation($operationType)
    {
        $operationType = strtoupper($operationType);

        return in_array(
            $operationType,
            [
                ActionTypes::CREATE,
                ActionTypes::UPDATE,
                ActionTypes::DELETE,
            ]
        );
    }
Validates operation type.

@param string $operationType

@return bool