Easy JSON Building

def p = new Expando(
    name:'Mary', 
    pets:[
        new Expando(name:'Fido', species:'Dog'),
        new Expando(name:'Snickers', species:'Cat')
    ]
)

def json = new JsonBuilder()
json( {
    name p.name,
    pets( p.pets.collect {[
        name:it.name,
        species:it.species
    ]})
})
JsonOutput.prettyPrint(json.toString())