@Override
        public IntWrapper createGenerationInstance(IntWrapper previous) {
            return new IntWrapper();
        }
Benchmark to compare ThreadLocalDirectory with java.util.concurrent's atomic
variables. Very low precision since it's an adapted unit test.

@author <a href="mailto:steinar@yahoo-inc.com">Steinar Knutsen</a>
vespajlib/developernotes/ThreadLocalDirectoryBenchmark.java