How do I write a custom Gatling feeder based off a JSON file that has certain values that are stubbed and need to be replaced before being sent? For example

{"payloads":[ {"groupId":"<GUID>", "epoch":<TIME>, "report":"somethingInteresting1"}, {"groupId":"<GUID>", "epoch":<TIME>, "report":"somethingInteresting2"}, {"groupId":"<GUID>", "epoch":<TIME>, "report":"somethingInteresting3"} ]} jsonFile("/opt/gatling/user-files/simulation/cannedPayloads.json")

won't work I think because it's not actually valid JSON in the file. I've tried: