Function zone_namespace_grant 

pub fn zone_namespace_grant(
    zone: &DNSZone,
    source_namespace: &str,
) -> NamespaceGrant

Classify how zone authorizes source_namespace, without logging.

An explicit listing is reported in preference to a wildcard when both are present: the grant would have been made regardless of the *, so it is not the wildcard’s doing and should not raise a cross-namespace warning.