spring boot 3.4.3 + TimedAspect causes thread to hang

[180254]

I have an application that stopped working correctly after updating to 3.4.3.
I have prepared a minimal app that reproduces the issue.

package com.example.demo;

import io.micrometer.core.annotation.Timed;
import io.micrometer.core.aop.TimedAspect;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Service;

@SpringBootApplication
public class DemoApplication {

  public static void main(String[] args) {
    SpringApplication.run(DemoApplication.class, args);
  }

  @Bean
  public TimedAspect timedAspect() {
    return new TimedAspect();
  }

  @Service
  public static class DemoService {
    public DemoService(DemoFactory demoFactory) {
      Thread initThread = new Thread(demoFactory::initSomething);
      initThread.setName("DemoService-initThread");
      initThread.start();
    }
  }

  @Service
  public static class DemoFactory {
    @Timed(value = "init_timed")
    void initSomething() {
      System.out.println("INIT SOMETHING");
    }
  }
}

Output when running the application on 3.4.2:

 :: Spring Boot ::                (v3.4.2)

2025-02-28T22:08:46.129+01:00  INFO 53499 --- [           main] com.example.demo.DemoApplication         : Starting DemoApplication using Java 21.0.6 with PID 53499 (/somepath/spring-boot-issue-0/target/classes started by pedziwia in /somepath/spring-boot-issue-0)
2025-02-28T22:08:46.132+01:00  INFO 53499 --- [           main] com.example.demo.DemoApplication         : No active profile set, falling back to 1 default profile: "default"
2025-02-28T22:08:46.700+01:00  INFO 53499 --- [vice-initThread] o.s.b.f.s.DefaultListableBeanFactory     : Creating singleton bean 'timedAspect' in thread "DemoService-initThread" while other thread holds singleton lock for other beans [timedAspect]
2025-02-28T22:08:46.715+01:00  INFO 53499 --- [           main] o.s.b.f.s.DefaultListableBeanFactory     : Creating singleton bean 'org.springframework.boot.actuate.autoconfigure.availability.AvailabilityHealthContributorAutoConfiguration' in thread "main" while other thread holds singleton lock for other beans []
INIT SOMETHING
2025-02-28T22:08:47.192+01:00  INFO 53499 --- [           main] com.example.demo.DemoApplication         : Started DemoApplication in 1.287 seconds (process running for 1.728)
Disconnected from the target VM, address: '127.0.0.1:58305', transport: 'socket'

Process finished with exit code 0

Output when running the application on 3.4.3:

 :: Spring Boot ::                (v3.4.3)

2025-02-28T22:09:46.824+01:00  INFO 53949 --- [           main] com.example.demo.DemoApplication         : Starting DemoApplication using Java 21.0.6 with PID 53949 (/somepath/spring-boot-issue-0/target/classes started by pedziwia in /somepath/spring-boot-issue-0)
2025-02-28T22:09:46.827+01:00  INFO 53949 --- [           main] com.example.demo.DemoApplication         : No active profile set, falling back to 1 default profile: "default"
2025-02-28T22:09:47.379+01:00  INFO 53949 --- [vice-initThread] o.s.b.f.s.DefaultListableBeanFactory     : Creating singleton bean 'timedAspect' in thread "DemoService-initThread" while other thread holds singleton lock for other beans [timedAspect]
2025-02-28T22:09:47.857+01:00  INFO 53949 --- [           main] com.example.demo.DemoApplication         : Started DemoApplication in 1.251 seconds (process running for 1.698)

The process does not terminate, it hangs forever and "INIT SOMETHING" is never printed.

I compared the classpath and found that downgrading the versions of two dependencies:

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-actuator-autoconfigure</artifactId>
  <version>3.4.2</version>
</dependency>
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-beans</artifactId>
  <version>6.2.2</version>
</dependency>

allows the program to start and work correctly again.

I have prepared a repository with a minimal app in Docker that reproduces this issue.
https://github.com/180254/spring-boot-issue-44498