ResolveHTTPSubjectResponse returns the concrete Gestalt subject a hosted HTTP
request should execute as. An unset subject means "fall back to the binding
subject". When reject_status is set, the host should reject the inbound
request with the provided status and message.
ResolveHTTPSubjectResponse returns the concrete Gestalt subject a hosted HTTP request should execute as. An unset subject means "fall back to the binding subject". When reject_status is set, the host should reject the inbound request with the provided status and message.