Hi,
We enforced require-bundle during the 0.9.x refactoring, because at the time, we had no idea where packages were coming from (Due to inconsistencies between plug-in and package names). Later, this has been enforced by a JUnit test (In BundleTests). When we first met the issue with Guava, we decided that this restriction wasn't required/helpful anymore, and we removed it (Or commented it out)
If package import is the way to solve the issue, then do not hesitate :)
At some point, we also discussed about replacing all our Guava APIs with Java 8 equivalents. I don't think we use any "Guava-only" class/interface in our public API anymore. However, since these issues/discussions always seem to occur around M6/M7 (i.e. after API freeze), I think nothing has been done in this direction.
We did also investigate Require-bundle + Reexport, as an alternative to Package Import + Use, but it didn't work. So I guess Java 8 (whenever possible) + Package Import/Use (for all remaining cases) is the way to go
Camille