ArrayList.subList

[Doug Lea]

While puzzling over why one of the demo videos on ForkJoin
out there required surprisingly high sequential thresholds, I
noticed that ArrayList.subList creates lists with per-access
overhead proportional to the sublist depth. Which is
not at all conducive to recursive use. Does anyone
know any reason why this was done? (No one who I
thought would know the answer does.) It is easy to keep
the overhead flat (we do so in CopyOnWriteArrayList and
the new jsr166e.extra ReadMostlyVector.)
If no one knows a reason not to, I'll put together a patch.
(I have a vague deja vu feeling that I might have done this
once before years ago...)

-Doug