31.0 has a bug that prevents GWT compilation from working.
Other Guava artifacts aren't affected, only users of GWT
. (If you are using GWT, you would know it.)
Sorry for missing this during release: It was a known issue
, and we had a partial workaround in place, but I forgot to include the problem in the list of release blockers.
I expect to be able to get a fixed release out within the next day or two.