While working on https://github.com/spring-projects/spring-boot/pull/44465 I noticed that DefaultJmsListenerContainerFactoryConfigurer#setObservationRegistry (introduced in 0321a8a0) is public unlike other setters in this class that are package-private. There are no usages of #setObservationRegistry outside of its package so this was likely by accident.
Comment From: snicoll
Thanks for the report. While there isn't any usage of it, it is now public in a GA version of Spring Boot so I am not sure if we could change that in a maintenance release. Flagging for team attention to see what the rest of the team think.