"Missing Parameter" warning for parameters set via environment variables

[aar0nr]

When setting parameters via environment variables, I get a "Missing Parameter" warning.

For example:

parameters:
  foo: ["%env(FOO)%"]

The %env(FOO)% will trigger the warning. I imagine when using env() the warning should be ignored since the parameter is resolved at runtime.

PS. env() was introduced in Symfony v3.2.

Ref: http://symfony.com/doc/current/configuration/external_parameters.html