OHTTP does require that the parties don't collude, which is why Google has engaged Fastly to run the relay service (which knows end user identifying data) and are themselves running the gateway service (which knows the end user request body).
Part of the contract terms include not delivering log data to Google for this service, among other things that help ensure that this separation of knowledge is upheld.
Part of the contract terms include not delivering log data to Google for this service, among other things that help ensure that this separation of knowledge is upheld.