While trying to build an older release (0.20.0) in Eclipse, I came
across a thread in the archives from a few months ago describing the
same problem I was having. It's unresolved on the list and though I
found a solution, I wasn't subscribed to common-dev at the time and so
I can't reply to it.
I saw the same set of errors, though with 0.20.0 instead of 0.20.1. I
believe this was a build path issue. Changing src/benchmarks to
src/benchmarks/gridmix2/src/java fixed it for me.
Hopefully this helps someone else trying to setup Eclipse with an older release.