Are there any use cases/examples of Watcher Conditions handling with Payload Data?
The simplest use case can be seen in the getting started section in ther reference doc ( https://www.elastic.co/guide/en/watcher/current/watch-log-data.html#log-add-condition). In this example, the compare condition simply extracts a value out of the payload and compares it to a given value.
For more complex conditions, you have the script. The cookbook section in the docs shows a few examples of evaluating marvel data. The conditions there are quite complex, but it just goes to show how far you can take it (here's one example: https://www.elastic.co/guide/en/watcher/current/watching-marvel-data.html#watching-cluster-health)