protected function checkForConflicts(array $uris)
    {
        $conflicts = $this->concentrator->getConflicts($uris);
        if (count($conflicts) > 0) {
            $conflict_list = '';
            $count = 0;
            foreach ($conflicts as $file => $conflict) {
                $conflict_list .= sprintf(
                    "\n- %s conflicts with %s",
                    $file,
                    implode(', ', $conflict)
                );

                $count++;
            }
            throw new SwatException(
                'Could not display head entries because the following ' .
                    'conflicts were detected: ' .
                    $conflict_list
            );
        }
    }