fix(tests): use getMessage() instead of getIn() for MDC test

[squakez]

Closes #8003

[squakez]

@JiriOndrusek I think this minor change will fix the problem raised in the test.

[JiriOndrusek]

@squakez Can you change the target branch to camel-main? Which would allow us to validate the fix with the CI?

[JiriOndrusek]

I tested locally on camel-main and the failure seems to be still there.

[squakez]

It could be a problem of initialization:

2025-11-25 09:09:40,979 WARN  [org.apa.cam.mdc.MDCService] (Camel (camel-1) thread #1 - timer://java) MDC: failed to store MDC data. This exception is ignored.: java.util.NoSuchElementException
	at java.base/java.util.ArrayDeque.removeFirst(ArrayDeque.java:362)
	at java.base/java.util.ArrayDeque.pop(ArrayDeque.java:593)
	at org.slf4j.helpers.ThreadLocalMapOfStacks.popByKey(ThreadLocalMapOfStacks.java:52)
	at org.slf4j.helpers.BasicMDCAdapter.popByKey(BasicMDCAdapter.java:159)
	at org.slf4j.MDC.popByKey(MDC.java:313)
	at org.apache.camel.mdc.MDCService.popAndClear(MDCService.java:189)
	at org.apache.camel.mdc.MDCService.userSelectedHeadersMDC(MDCService.java:202)
	at org.apache.camel.mdc.MDCService.setOrUnsetMDC(MDCService.java:114)
	at org.apache.camel.mdc.MDCService.unsetMDC(MDCService.java:135)
	at org.apache.camel.mdc.MDCProcessorsInterceptStrategy$1.process(MDCProcessorsInterceptStrategy.java:66)
	at org.apache.camel.support.processor.DelegateAsyncProcessor.process(DelegateAsyncProcessor.java:117)
	at org.apache.camel.processor.errorhandler.RedeliveryErrorHandler$SimpleTask.handleFirst(RedeliveryErrorHandler.java:440)
	at org.apache.camel.processor.errorhandler.RedeliveryErrorHandler$SimpleTask.run(RedeliveryErrorHandler.java:416)
	at org.apache.camel.impl.engine.DefaultReactiveExecutor$Worker.doRun(DefaultReactiveExecutor.java:199)
	at org.apache.camel.impl.engine.DefaultReactiveExecutor$Worker.executeReactiveWork(DefaultReactiveExecutor.java:189)
	at org.apache.camel.impl.engine.DefaultReactiveExecutor$Worker.tryExecuteReactiveWork(DefaultReactiveExecutor.java:166)
	at org.apache.camel.impl.engine.DefaultReactiveExecutor$Worker.schedule(DefaultReactiveExecutor.java:148)
	at org.apache.camel.impl.engine.DefaultReactiveExecutor.scheduleMain(DefaultReactiveExecutor.java:59)
	at org.apache.camel.processor.Pipeline.process(Pipeline.java:162)
	at org.apache.camel.impl.engine.CamelInternalProcessor.processNonTransacted(CamelInternalProcessor.java:370)
	at org.apache.camel.impl.engine.CamelInternalProcessor.process(CamelInternalProcessor.java:346)
	at org.apache.camel.component.timer.TimerConsumer.sendTimerExchange(TimerConsumer.java:293)
	at org.apache.camel.component.timer.TimerConsumer$1.doRun(TimerConsumer.java:164)
	at org.apache.camel.component.timer.TimerConsumer$1.run(TimerConsumer.java:136)
	at java.base/java.util.TimerThread.mainLoop(Timer.java:566)
	at java.base/java.util.TimerThread.run(Timer.java:516)

This is not happening in regular runtime. I'm troubleshooting and fix either here or on the core project.

[squakez]

I investigated and it seems that Quarkus does not like MDC push/pop which we had introduced recently. I am closing this PR and I will try to use MDC put/delete instead in order to prevent Quarkus runtime to fail.