Exploring Google Guava
These sorts of high-level utilities have always been missing in Java. It’s probably a good idea to collect them in one place. Would kind of prefer that place be Apache.
Social Networking vs Email
I find it very, very unlikely that more people are more interested in their social network than in their email. This is almost a contradiction as, by definition, nothing is more relevant than your email.
Links instead of PATCH
PATCH is an interesting attempt to hide custom application semantics behind the uniform document/resource model. This is the central idea behind REST and, well, if you’re going to go, you might as well go hard. I am concerned that PATCH is too ‘text-oriented’, even the name is a bit strange, and I wonder why people don’t just use POST?