Why do you think this is wrong? If we're considering the customers that need to use a different environment, and also considering our own internal purposes (we use the SDK to point to other environments frequently), we will need that setter in the interface. 

If this turns out to be tragically wrong for whatever reason, we should at least provide a way that we can specify a different URL that is not meant to be usable by customers (but I really don't see why we shouldn't have this).