'preserve_placeholders' is not a supported key

I'm obviously okay with the config schema change, but I'm going to skip the other unrelated changes. Especially the introduction of the PHP attribute, since that would require us to drop support for certain older Drupal versions and I don't feel like that's absolutely necessary at this point.

Do we need to add an update hook that converts existing preserve_placeholders values to booleans or is this something which is being done automatically?

Just tested it myself and it looks like that's not necessary, values are being casted automatically.

Automatically closed - issue fixed for 2 weeks with no activity.