Getting reify classes to work

I’m trying to work through the examples here:

But I can’t seem to get any “ruby.Foo” instances in my output from jmap.

Is that documentation still accurate?
Is -J-Djruby.reify.classes=true still the right option?
Do I need java 1.7?

Window 1:

/home/dev/tmp $ jruby -J-Djruby.reify.classes=true foo_heap_example.rb
ready for analysis!

Window 2:
/home/dev/tmp $ jps
11767 Jps
10218 Main
/home/dev/tmp $ jmap -histo:live 10218 |grep " ruby."
(provides no output)

Have tried on a linux box with:

jruby -v
jruby 1.6.0.RC1 (ruby 1.8.7 patchlevel 330) (2011-01-17 9c0cba9) (Java
HotSpot™ Client VM 1.6.0_26) [linux-i386-java]
java -version
java version “1.6.0_26”
Java™ SE Runtime Environment (build 1.6.0_26-b03)
Java HotSpot™ Client VM (build 20.1-b02, mixed mode, sharing)

And also on a windows 7 machine with:

jruby -v
jruby 1.6.4 (ruby-1.8.7-p330) (2011-08-23 17ea768) (Java HotSpot™
Client VM 1.6.0_13) [Windows Vista-x86-java]
java -version
java version “1.6.0_26”
Java™ SE Runtime Environment (build 1.6.0_26-b03)
Java HotSpot™ Client VM (build 20.1-b02, mixed mode, sharing)

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