Have attempted to do my own assignment like so:
{"error":{"id":"4367DBC77C9A6AE7","timestamp":1571282318000000,"trace_id":"70C8BA2D755B5AE570DBA0807F14A684","transaction_id":"5E3768BB0EF5FBAC","parent_id":"5E3768BB0EF5FBAC","culprit":"TTransactionWithSpansTest.Load","grouping_key":"403","exception":{"code":"403","message":"HTTP/1.1 403 Forbidden","attributes":null,"stacktrace":null,"type":"EIdHTTPProtocolException","handled":true}}}
and I get a 200 back. However when I look up the error in ES the grouping_key has been changed. And for some reason all my errors are being assigned the same grouping_key.