Get build number using Jenkins.NET

JenkinsNet_GetBuildNumber.cs

// Enqueue a new build and get queue #
JenkinsBuildResult buildResult = client.Jobs.Build(jobName);
int? queueItemNumber = buildResult.GetQueueItemNumber();

// Poll queue item until build number is available
int? buildNumber = null;
while (!buildNumber.HasValue) {
    var queueItem = client.Queue.GetItem(queueItemNumber.Value);
    buildNumber = queueItem?.Executable?.Number;
    if (buildNumber.HasValue) break;

    Thread.Sleep(200);
}

return buildNumber.Value;