Sample Groovy code to transform a Map into a Json output

map-to-json.groovy

def someMap = [
  'key1': "value",
  'key2': 142.1
  ]

def json = new groovy.json.JsonBuilder()

json rootKey: someMap

println "json output: "
println groovy.json.JsonOutput.prettyPrint(json.toString())

Displays:

json output: 
{
    "rootKey": {
        "key1": "value",
        "key2": 142.1
    }
}

Thanks!