Parse JSON into a special format using Groovy

I have a JSON file that I need to parse and output a string based on the fields in JSON.

Language to be used: Groovy

Required output: (note:series first)

SF3000IG,Left Vertical,A,Anchored@SF3000IG,Right Vertical,A,Anchored@SF3000IG,# Horizontal Mullions,N,None@SF3000IG,Glazed/Unglazed,G,Glazed

Notes:
- This columns list can grow to 1000 lines maybe, so needs to be dynamic. But format will remain same, that is, ":" will always be there.