Google platform integration

I have followed the tutorial for setting up a Pub/Sub topic, and have setup an integration to publish to google. But when I TEST it, it times out. Publishing from a photon returns 404 errors. Any ideas?

Did you find a solution to your problem? For three days I have been trying and have not gotten 404 errors but repeatedly 400 errors:

{"error":{"code":400,"message":"Invalid value at 'messages[0].attributes[3].value' (TYPE_STRING), 0","status":"INVALID_ARGUMENT","details":[{"@type":"","fieldViolations":[{"field":"messages[0].attributes[3].value","description":"Invalid value at 'messages[0].attributes[3].value' (TYPE_STRING), 0"}]}]}}

I went through all the steps in setting up the GCP project with no issues.