Grails Holder class
===

I found this class ([Holder][1]) in the groovy javadocs, but the javadoc is empty...does anyone know what it does?  
It seems that works like a _ThreadLocal_ which if it is, which is better? What pros? What cons?  

Cheers


  [1]: http://grails.org/doc/2.0.1/api/grails/util/Holder.html