Unnecessary `services/config` calls or empty response

[Tomgroot]

In sendRequestMultiCore, the services/config endpoint is called to fetch the tgu domains. How should we handle the unnecessary calls this will generate? Currently, this endpoint returns an empty response, which will skip the request altogether.

Would the approach here be suitable: https://github.com/opentickettech/paynl-omnipay/pull/1/files? In it, tguDomain is passed as a parameter to the request, and a tgu domain list is built (somewhat "hard-coded") from this.

[NickHes]

@Tomgroot thanks for your suggestion and PR. Your reasoning is sound. The team is going to take a look at this early next week and merge it upstream.