Add auto-configuration for JmsClient.Builder

[vpavic]

This commit adds auto-configuration for JmsClient.Builder prototype bean in order to enable reuse of preconfigured instances for further customization (for example, message conversion), similar to usages of JsonMapper.Builder, RestClient.Builder and others that follow the same pattern.

[snicoll]

@vpavic can you please clarify (besides consistency) what you're looking for here? Contrary to the builder you've described, JmsClient.Builder has currently no pre-configuration.

[vpavic]

I'm not looking for consistency (that's just a side effect) but rather exactly what commit message describes:

• ability to provide common configuration using spring.jms.template.* properties - this is what preconfigured client builder instances will effectively provide
• ability to take such client builder and apply application-level customizations, most commonly message converters, according to specific needs of individual destinations application interacts with

This is analogous to how I use JsonMapper.Builder and RestClient.Builder instances provided by Spring Boot.

While migrating one project from JmsTemplate to JmsClient I noticed latter contains Builder contract - which was the trigger for this contribution, as it provides potential for simplifying things because I would no longer need to configure multiple JmsTemplate beans.

[snicoll]

exactly what commit message describes

I read the commit if that's what you were trying to point out.

The problem here is that the builder is created by a JmsTemplate that could be the one of the auto-configuration but it could be the one from the user. If it is the one from the user, then you end up with a builder that's provided with settings from whatever the user has defined.

This is analogous to how I use JsonMapper.Builder and RestClient.Builder instances provided by Spring Boot.

It isn't. The change is too weak at this point to be considered. If we provide a builder it must always be provided with the auto-configuration applied to it and the curent API makes it quite hard to do so. That's also why this wasn't provided in the first place.