JSONPath expression including a filter that uses a RegExp

I have now gone down the route of implementing the filter logic in Groovy (since I have to use a Grrovy script to do some casting of return types as discussed in my other post here http://community.smartbear.com/t5/SoapUI-Open-Source/JSON-integer-property-being-transferred-as-a-float/m-p/116747).

If anyone does find the correct syntax, please share :)