pub fn build(config: &Config) -> Result<Arc<FilterPolicy>>Expand description
Builds the admin listener’s policy from admin.filter, refusing anything
that could not decide here.
With no rules, the policy filters nothing but still carries
trusted_proxies, so the client address is resolved the same way whether
or not a rule is written. The engine’s own builder is skipped in that case:
its “no rules” warning speaks of certificates, which this listener issues
none of.