The headers several app layers each add a line of: the facets that declare
one render a line each, in registry order (the layers' order), and the wire
carries the lines joined with a comma. Every other header is declared by
exactly one facet (the registry test enforces both).
The headers several app layers each add a line of: the facets that declare one render a line each, in registry order (the layers' order), and the wire carries the lines joined with a comma. Every other header is declared by exactly one facet (the registry test enforces both).