extensionsAs
Decodes the whole extension map into T. This is the typed consuming edge.
Extension members T does not declare are ignored, so a partial view is fine. So is reading a document produced by a newer version of the problem type than T was written against. §3.2 requires this, not just a convenience: "consumers MUST ignore extension members they don't recognize". It holds regardless of json. ignoreUnknownKeys gets re-applied on top of a caller's instance, so a strictly configured application instance cannot turn a conforming document into an exception. Everything else about json, its serializersModule above all, stays the caller's.
See also
Decodes the whole extension map into T, with the deserializer resolved from T. Members T does not declare are ignored, as RFC 9457 §3.2 requires.
Samples
problem.extensionsAs<OutOfCredit>()