List of steps to reproduce (step by step, including full links if applicable):

• declare a cargo field with String (allowed values=Group A (female), Group B (male))

What happens?:
An invalid field description error is thrown

What should have happened instead?:
It should pass field description validation

Our clients need this, so I wrote a patch for it. I am not really sure. See https://gerrit.wikimedia.org/r/c/mediawiki/extensions/Cargo/+/802764