public void performPushEvent(Event event) {
    Preconditions.checkNotNull(event.getCommits(), "commits array can not be null");
    // For each commit, extract jira issues
    Multimap<String, Commit> jiraIssues = ArrayListMultimap.create();
    event
        .getCommits()
        .forEach(
            commit ->
                jiraService
                    .extractIssuesFromMessage(commit.getMessage())
                    .forEach(issue -> jiraIssues.put(issue, commit)));

    if (jiraIssues.size() > 0) {
      User user = getUser(event);

      jiraIssues
          .asMap()
          .forEach(
              (issue, commits) ->
                  commentIssue(event.getRepository().getName(), user, commits, issue));
    }
  }