private function buildContributorsList(array $issues) : array
    {
        $contributors = [];

        foreach ($issues as $issue) {
            foreach ($issue->getContributors() as $contributor) {
                $contributors[$contributor] = $contributor;
            }
        }

        return array_values($contributors);
    }
private function buildContributorsList(array $issues) : array
    {
        $contributors = [];

        foreach ($issues as $issue) {
            foreach ($issue->getContributors() as $contributor) {
                $contributors[$contributor] = $contributor;
            }
        }

        return array_values($contributors);
    }
@param Issue[] $issues

@return string[]