Update batch endpoint to get URL from discovery

[chrisdunelm]

Discovery docs now include the path to the batch endpoint. This should be used instead of hardcoding it to /batch.

[LindaLawton]

If you are referring to batchPath. How do you intend to check for APIs which don't support the normal Google API batching endpoint.

Example:

https://www.googleapis.com/discovery/v1/apis/analyticsreporting/v4/rest

Which appears to also have the batchPath set. The Google Analytics reporting API v4 does not support the normal Google API batching endpoint.

[chrisdunelm]

@LindaLawton I'm working on this now. In what way does this not support the normal Google API batching endpoint?
Retrieving the batch endpoint from the discovery doc will mean it will use "https://analyticsreporting.googleapis.com/batch".
Do you mean this API just doesn't support batching at all? In which case nothing will change, and users will get errors if they try to batch.
Or do you mean that the discovery-doc endpoint is wrong, and it must in fact use "http://www.googleapis.com/batch" (the current hard-coded value)?

[LindaLawton]

Reporting API is batching by nature so it doesn't support the normal Google batching endpoint that would be double batching.

I guess errors work I may speak with the team see if the endpoint should be removed

[chrisdunelm]

OK, so after this change it'll fail in the same way that it used to if someone tries to use batching.
That's fine.
Thanks.