Typo in Fix for #172

[tuliren]

In this commit, when setting upstream URL, a wrong parameter was checked:

String upstreamUrl = (String) cause.get("upstreamUrl");
if (!Strings.isNullOrEmpty(upstreamProject)) {
 cause_object.setUpstreamUrl(upstreamUrl);
}

[khmarbaise]

Can you please make a pull request of it so I can merge it ?

[tuliren]

@khmarbaise, yes, I have created a PR here: #283

Thanks.