problemXml

Registers the application/problem+xml converter on Ktor's own ContentNegotiation.

Call this after problemJson(). Registration order decides which format an absent or wildcard Accept resolves to, and JSON is meant to win that tie; registering XML first silently reverses it, which NegotiationIntegrationTest pins in both directions. Nothing else in a typical application registers application/problem+xml, so unlike the JSON side there is no converter race to worry about here.

There is no acceptPlainXml counterpart to problemJson's acceptPlainJson: a client sending Accept: application/xml is asking for that application's own XML dialect, and answering every such request with a problem document would take over a media type this library does not own. The JSON flag exists because tooling overwhelmingly sends application/json and nothing else; no equivalent convention exists on the XML side.