Function feature_update_decision 

pub fn feature_update_decision(
    facts: FeatureUpdateFacts,
) -> FeatureUpdateDecision

Decide one feature row from the host’s facts.

A rejection names the first rule that fails in the order of Kafka’s FeatureControlManager.updateFeature. A metadata.version downgrade is admitted only when no level between the two changed metadata, whatever the downgrade type, and an admitted metadata.version row never writes anything but its feature-level record.