It is kind of a dumb test to do 'new HashMap' with the default initialCapacity then cram stuff into it in a tight loop. It is basically testing constant rehash

It is kind of a dumb test to do 'new HashMap' with the default initialCapacity then cram stuff into it in a tight loop. It is basically testing constant rehashes which is obviously going to generate a ton of garbage I suspect the default collection implementations would perform significantly better if they were used correctly