What is the Validation URL?

[humblevladimirthegreat]

Hello,
When attempting to use api-first-hand (with Lightbend activator), I run into the following error when compiling using my swagger api (OpenAPI 2.0) yaml file:

java.lang.IllegalStateException: Validation URL is required for play security code generator

Full stack trace available here: https://pastebin.com/iUiLBcsA
I can't find any mention of a validation url in the OpenAPI spec. Can someone please explain what this is, and how to specify it? Thanks

[humblevladimirthegreat]

Figured it out by looking at the example.yaml file. I needed to add the special vendor extension field x-token-validation-url to my security definition. I'm not sure if it mattered, but I also added x-api-first-error-mapping to my top level definitions. Some official documentation describing this would have been appreciated.