Code example for Ardor bundler code snippet to filter transactions of a certain criteria to pay ZERO 0 ignis Fees?
Take a look at the bundler filter shipped with Ardor: src/java/nxt/addons/AccountPropertyBundler.java and PersonalBundler.java

You need to be familiar with internal Ardor interfaces in order to write your own bundler filter.  The bundler filter runs as part of the server and is loaded during server initialization.  

You specify a custom bundler in nxt.properties by setting nxt.bundlingFilter.