KongPlugin request-transformer reading value from k8s secret

What would be best way to pick up values from k8s secret in KongPlugin config?

apiVersion: configuration.konghq.com/v1
kind: KongPlugin
    - Authorization:Basic $(<<reading from K8S secret >>)
plugin: request-transformer

Should I create an own version of this plugin, where value should be an
name of secret and then read value of secret in lua code? (is it possible?)
Or is there any other way get values from secrets?

Business reason: avoid to keep confidential values in repository with KongPlugin configuration.

You can use configFrom to supply the entire configuration from a secret: