Construct a JSON document with groovy.json.JsonBuilder

def builder = new groovy.json.JsonBuilder()
def myMap = [:]

myMap.put('name', 'Dynamically generated approval Pprocess')
myMap.put('rootActivity', ['type':'graph'])
myMap['rootActivity'] +=  ['name':'auto'] 

builder.call( myMap )

println builder.toPrettyString()