I think the point rmrfrmrf is making is that Guava is a typical example of Google's attitudes towards the two-way relationship of open source. Google developers (and many other big software companies) are more than happy to open their code and promote it as something that the community should adopt, but seem rigidly dismissive of any code contributions to the project from outside. That may not be the case for every Google project but it does feel like it's a common one to me.

What Google projects would make good counterpoints by demonstrate a welcoming attitude to external contributions?