This is the "virtual mbeans" code example from OpenDMK. It displays the filesystem as a "virtual mbean" so that you can browse it from the jconsole without actually creating any mbeans.
The Oracle documentation from the Java Dynamic Management Kit 5.1 Tutorial is here:
http://docs.oracle.com/cd/E19698-01/816-7609/6mdjrf85d/index.html
Note that this project does NOT rely on any DMK code or libraries, but can be run right out of the box.
The original example used MBeanServerInterceptor, but for JDK 1.5 only the MBeanServer interface is required -- the MBeanServerInterceptor interface is basically there to tell you which methods can throw UnsupportedOperationExceptions.
The original DMK examples are lost to history. They are not available on the Oracl website, and I pulled the code from https://github.com/javaee/hk2-extra/tree/master/experiments/jmx
This code has been modified to work with JDK 1.8 with a default methods MBeanServerInterceptor and use MBeanServer as the base interface.