When virtual threads are enabled, configure Spring Integration's task scheduler to use them

[facewise]

Motivation

Former IntegrationAutoConfiguration.IntegrationTaskSchedulerConfiguration was not aware of virtual threads. It means ThreadPoolTaskScheduler was instantiated regardless of capability of virtual threads when you use spring-boot-starter-integration.

Changes

Now IntegrationAutoConfiguration.IntegrationTaskSchedulerConfiguration determines a proper TaskScheduler bean to be instantiated via @ConditionalOnThreading.

If virtual threads is enabled, SimpleAsyncTaskScheduler will be instantiated, otherwise works as is.

This can resolve #41188.

[mhalbritter]

Thanks a lot!

[facewise]

@mhalbritter Oh, I think I made a broken test. Sorry.
I don't know how to run virtual threads enabled tests with @EnabledForJreRange(min = JRE.JAVA_21) on my pc.

[mhalbritter]

Don't worry, I'll fix it. The command to run is gradle test -PtoolchainVersion=21.

[facewise]

Thank you.