YAML payload parsing

[PGriffith]

The 'right' way to do it would be to create a custom module that brought a Java YAML parser into scope - it looks like the two main candidates are Jackson or 'snakeyaml'.
The 'easy' way to do it would be to use the 'hack' described here:

Importing and using 3rd party Java jar libraries in Ignition

For gateway-only access you can also just drop jar files into the lib/core/gateway folder (and then restart). Just don’t expect these to be part of any backups, available outside gateway scope, or available on another Ignition gateway unless you put them there also. Basically, you need to remember that you added those jars, else your project may someday stop working because you’ve found yourself running on an installation that does not have them.

If you drop the snakeyaml .jar file in the right location, the gateway will automatically load it to the classpath on the next restart, which will then make it available from scripting.