@TaskAction
    fun check() {
        val contributorsInReleaseNotes = TreeSet(getContributorsInReleaseNotes().map { it.login })
        val contributorsFromPullRequests = TreeSet(getContributorsFromPullRequests().map { it.login })
        val contributorsInPullRequestsButNotInReleaseNotes = contributorsFromPullRequests.minus(contributorsInReleaseNotes)

        if (contributorsInPullRequestsButNotInReleaseNotes.isNotEmpty()) {

    @TaskAction
    fun update() {
        val contributorsInReleaseNotes = getContributorsInReleaseNotes().associateBy { it.login }
        val contributorsFromPullRequests = getContributorsFromPullRequests().associateBy { it.login }

        val unrecognizedContributors = contributorsFromPullRequests.keys - contributorsInReleaseNotes.keys
        if (unrecognizedContributors.isNotEmpty()) {

    }

    @Internal
    protected
    fun getContributorsFromPullRequests(): Set<GitHubUser> {
        if (!milestone.isPresent) {
            error("Milestone not set: please rerun the task with `--milestone <milestone>`")
        }