Symfony version(s) affected: 4.1
Description
I want to be able to configure swiftmailer delivery_adresses via env var. In prod env on production server it should be null, in prod env on staging server it should have some value. Looks like work for env parameters.

I try to set it like

swiftmailer:
    delivery_addresses: '%env(json:MAILER_DELIVERY_ADDRESSES)%'

I specify json env processor, and in my env file

MAILER_DELIVERY_ADDRESSES='["[email protected]"]'

A dynamic value is not compatible with a "Symfony\Component\Config\Definition\PrototypedArrayNode" node type at path "swiftmailer.mailers.default.delivery_addresses".

Json processor return array, and so it should be valid to pass such value to PrototypedArrayNode.