Kong plugin response-transformer example? [solved. PEBCAK.]

I’m having a bit of a time discovering the correct YAML incantation for a response-transformer config.

This causes db-less Kong to complain:

apiVersion: configuration.konghq.com/v1
kind: KongPlugin
metadata:
  name: add-headers
  namespace: default
config:
  add.headers:
  - X-Frame-Options:DENY
plugin: response-transformer

… So what am I doing wrong this time?

Obviously, five minutes after posting, the answer comes to me as:

config:
  add:
    headers:
    - X-Frame-Options:DENY
    - X-XSS-Protection:1

… So that’s PEBCAK again.