Describe the bug

I mentioned that custom serialization for Multi doesn't work because serialization flow goes roughly like this:

• org.jboss.resteasy.reactive.server.core.StreamingUtil#serialiseEntity
• io.quarkus.resteasy.reactive.jackson.runtime.serialisers.FullyFeaturedServerJacksonMessageBodyWriter#writeTo
• org.jboss.resteasy.reactive.server.jackson.JacksonMessageBodyWriterUtil#doLegacyWrite

Which effectively means that custom serialization is ignored because that one would require non-default writer as when io.quarkus.resteasy.reactive.jackson.runtime.serialisers.FullyFeaturedServerJacksonMessageBodyWriter#writeResponse is called.

Expected behavior

I didn't find documented that this shouldn't work for the Multi reactive type, therefore I would expect it to work.

Actual behavior

Custom serialization is not applied.

How to Reproduce?

I have tests for this: d321267 just uncomment io.quarkus.resteasy.reactive.jackson.deployment.test.ResponseType#MULTI and run mvn clean test -f extensions/resteasy-reactive/rest-jackson/deployment/ -Dtest=SecureFieldDetectionTest

Output of uname -a or ver

Fedora 38

Output of java -version

OpenJDK 21

Quarkus version or git rev

999-SNAPSHOT

Build tool (ie. output of mvnw --version or gradlew --version)

Apache Maven 3.9.4

Additional information

No response