Upgrade from 3.3.x to 3.4.x and 4.0.0: SpringBootTests throw OutOfMemoryError

• In our test setup code, we have a ContextConfiguration which adds beans to the application context (MockWebServer and GreenMail instances, which are shut down on ContextClosedEvent by calling their stop() and shutdown() methods)
• The SpringBootTests additionally use the following annotations: @DirtiesContext(classMode = AFTER_EACH_TEST_METHOD) and @TestInstance(PER_METHOD)
• With Spring Boot 3.3.5 the tests execute successfully
• With 3.4.1 and 3.4.2 and 4.0.0 the tests fail with an out of memory exception (java.lang.OutOfMemoryError: Java heap space)
• When profiling the test runs, we observe that over 400 instances of org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext are referenced from org.springframework.beans.factory.support.DefaultListableBeanFactory. It appears that this is about one instance per SpringBootTest.
• With 3.3.5, the profiler (YourKit) marks them as [Weak/Soft Reachable], whereas in 3.4.1 it doesn't (are they strong references now?)
• We are not sure if there is a new leak, or if existed before and only now exhausts heap space

Example stacktrace:

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'xyz' defined in class path resource [abc.class]: Unexpected exception during bean creation
	at app//org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:536)
	at app//org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:336)
	at app//org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:289)
	at app//org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:334)
	at app//org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199)
	at app//org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:254)
	at app//org.springframework.beans.factory.support.DefaultListableBeanFactory.addCandidateEntry(DefaultListableBeanFactory.java:1883)
	at app//org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1847)
	at app//org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveMultipleBeanCollection(DefaultListableBeanFactory.java:1737)
	at app//org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveMultipleBeans(DefaultListableBeanFactory.java:1705)
	at app//org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1580)
	at app//org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1519)
	at app//org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:913)
	at app//org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:791)
	... 100 more
Caused by: java.lang.OutOfMemoryError: Java heap space

Environment:

• JDK Version: OpenJDK Runtime Environment Temurin-21.0.5+11 (build 21.0.5+11-LTS)
• Operating System: Windows 11
• Spring Boot Version: 3.4.1 (issue occurs), 3.3.5 (no issue)
• Build system: Gradle Wrapper 8.12

Attempted solutions:

• Set server.shutdown to immediate
• Tried jetty and undertow instead of tomcat

Additional information:

• We observe the same behaviour error with 3.4.2 and 4.0.0 (originally tested with 3.4.1)
• 3.3.x shows basically the same increase in heap memory usage over time like in this screenshot of our profiler. However, 3.3.x doesn't trigger the out of memory error.