env.WHATEVER not considered for environment variable cross reference resolution in Declarative

With an environment section like this:

environment {
  FOO = "something"
  BAR = "${env.FOO} else"
}

The EnvVars-driven environment variable resolution/expansion doesn't know that env.FOO means that it needs to resolve FOO before resolving BAR, so there's no guarantee that'll actually happen in that order, and you may well get BAR as null else.