Cannot find class files for mapping in the IDE , when select others

This stems from a conversation in the comments on this blog post: http://tools.jboss.org/blog/2015-06-01-so-you-want-to-transform-part-1.html

I'm using JBoss development studio version - 8.1.0.GA and trying to simulate the sample csv-to-xml .When I tried to added a new transformation by selecting both the source and destination to 'Others', in my second step , when I try to select the source file , i just gives me an empty pop up with out identifying the java class.
Please help me with this (Is there anything im missing or is it the version issue) ???