We are using a JSR223 code to make an json object using below code,

def mandatory = new groovy.json.JsonSlurper().parse(prev.getResponseData()).Properties.Room.Extras.findAll { extra -> extra.IsMandatory }

def payload = []
mandatory.each { extra ->
    def item = [:]
    item.put('ExtraId', extra.ExtraId)
    item.put('OptionId', extra.Options[0].OptionId)
    item.put('ExpectedNetCost', extra.Options[0].NetCost)
    payload.add(item)
}

vars.put('payload', new groovy.json.JsonBuilder([Extras: payload]).toPrettyString())

we are using ‘toPrettyString’ as well but still getting an extra pair of curly braces (at the start and end).
Can someone please help to remove this !

I have tried this link After updating json file with groovy, the file data contains extra curly brackets and “content” object

but solution doesn’t work for me.