Supply a value for http client?

[sheam]

We are using the fetch template with the typescript generator. When we generate clients, we have to always supply a rootUrl and http argument. Our http parameter does some extra checks, and assigns credentials. It would be nice to have this generated.

For the rootUrl, the generator generates this:
this.baseUrl = this.getBaseUrl("", baseUrl);
So it seems that the solution is to a base class which supplies the getBaseUrl function. This is fine with us, as we need a base class to supply the date reviver anyway.

However, there doesn't seem to be a way to have a default argument for the http parameter, it is always generated as:
this.http = http ? http : window as any; I really don't want to assign something to window.fetch, in case it breaks a 3rd party. It would be nice if that argument worked like it does for the baseUrl.

I suppose I could override the Fetch template.... What have others does in this scenario?