Guava team recommends MultimapBuilder over specific Multimap
implementations, so callers don't have to know the specific key/value
behaviors of the individual implementations. The static factory
methods in the implementations will be removed in a later version.
LinkedListMultimap and LinkedHashMultimap are not affected, since
MultimapBuilder lacks support for specifying linked entries, and thus
the factory methods are not in immediate danger of deletion.
Change-Id: I7744db687da84a7beae31d1cb8953e782ed23c1d
0ecf8cf401