Small feature request: The mutable serializer has a hard-coded default of JSON. If a user defines a custom map of mime types to serializers that doesn't include JSON, they are still forced into that default. We should make the default/fallback configurable.
Small feature request: The mutable serializer has a hard-coded default of JSON. If a user defines a custom map of mime types to serializers that doesn't include JSON, they are still forced into that default. We should make the default/fallback configurable.