Here's a minimal example of a Tizen Web Application to show url=null.
The readme includes some instructions to setting up a Tizen development environment in order to be able to run the project. It's a "rather" heavy process.
I encountered this while setting up IMA and AdManager to serve ads into a Tizen Smart TV environment. Specifically, I'm attempting to get AdExchange to supply ads.
I AM able to get valid ads from non-programmatic channels such as a test VAST-response configured into our AdManager, even when the url-parameter is null, but AdX never returns ads for Tizen. The same codebase, when run in a browser, does receive ads from AdX.
I'm not entirely sure that fixing this parameter is all that would be required to make AdX supply ads for Tizen, since the parameters with which IMA calls AdManager are very different when running the code in browser and when running it in Tizen.
In our production code, I added a description_url pointing to our web-content, but that did not help matters.
Do you know if getting AdX to participate in supplying ads into Tizen through IMA is even possible?
As for the popularity of any of this, I wouldn't know.