Solved
JsonOutput.toJson adding \
def mainElement= element1: [ {"key" : "value", "key2" : "value2","element2": [{ "key3" : "value3"}, {"key4" : "value4"} ] element2 was already formed with JsonOutput.toJson JsonOutput.toJson(mainEl...
thanks for your reply.
when i use this json for further tests the \ char is not causing any problems. So i let it remain in the json.
