Spring WebMVC With Coroutines - Filters Break Tests

Spring Boot Version: 3.4.2 Java Version: 21

When using spring web-mvc with kotlin coroutine support, adding a filter into the security chain appears to break the test completely

Reproducer project: https://github.com/austinarbor-wk/spring-webmvc-coroutines

If you run the tests as-is, the async test succeeds. If you uncomment line 31 in SecurityConfig (which adds a simple logging filter), then the async tests start failing.

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( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
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 :: Spring Boot ::                (v3.4.2)

2025-02-20T12:57:36.341-05:00  INFO 12578 --- [    Test worker] dev.aga.controller.SomeControllerTest    : Starting SomeControllerTest using Java 21.0.5 with PID 12578 (started by austinarbor in /Users/austinarbor/git/wk/spring-webmvc-coroutines)
2025-02-20T12:57:36.342-05:00  INFO 12578 --- [    Test worker] dev.aga.controller.SomeControllerTest    : No active profile set, falling back to 1 default profile: "default"
2025-02-20T12:57:36.851-05:00  WARN 12578 --- [    Test worker] .s.s.UserDetailsServiceAutoConfiguration : 

Using generated security password: 68b959c1-9150-4758-8799-f3a357dcbf6d

This generated password is for development use only. Your security configuration must be updated before running your application in production.

2025-02-20T12:57:36.863-05:00  INFO 12578 --- [    Test worker] r$InitializeUserDetailsManagerConfigurer : Global AuthenticationManager configured with UserDetailsService bean with name inMemoryUserDetailsManager
2025-02-20T12:57:37.118-05:00  INFO 12578 --- [    Test worker] o.s.b.t.m.w.SpringBootMockServletContext : Initializing Spring TestDispatcherServlet ''
2025-02-20T12:57:37.118-05:00  INFO 12578 --- [    Test worker] o.s.t.web.servlet.TestDispatcherServlet  : Initializing Servlet ''
2025-02-20T12:57:37.119-05:00  INFO 12578 --- [    Test worker] o.s.t.web.servlet.TestDispatcherServlet  : Completed initialization in 1 ms
2025-02-20T12:57:37.137-05:00  INFO 12578 --- [    Test worker] dev.aga.controller.SomeControllerTest    : Started SomeControllerTest in 0.917 seconds (process running for 1.43)
2025-02-20T12:57:37.587-05:00  INFO 12578 --- [    Test worker] d.a.config.SecurityConfig$LoggingFilter  : foo

MockHttpServletRequest:
      HTTP Method = POST
      Request URI = /endpoint
       Parameters = {}
          Headers = [Content-Type:"application/json;charset=UTF-8", Content-Length:"10"]
             Body = {"a": "b"}
    Session Attrs = {}

Handler:
             Type = null

Async:
    Async started = false
     Async result = null

Resolved Exception:
             Type = null

ModelAndView:
        View name = null
             View = null
            Model = null

FlashMap:
       Attributes = null

MockHttpServletResponse:
           Status = 200
    Error message = null
          Headers = [Vary:"Origin", "Access-Control-Request-Method", "Access-Control-Request-Headers", X-Content-Type-Options:"nosniff", X-XSS-Protection:"0", Cache-Control:"no-cache, no-store, max-age=0, must-revalidate", Pragma:"no-cache", Expires:"0", X-Frame-Options:"DENY"]
     Content type = null
             Body = 
    Forwarded URL = null
   Redirected URL = null
          Cookies = []

Async not started
java.lang.AssertionError: Async not started
    at org.springframework.test.util.AssertionErrors.fail(AssertionErrors.java:39)
    at org.springframework.test.util.AssertionErrors.assertTrue(AssertionErrors.java:73)
    at org.springframework.test.web.servlet.result.RequestResultMatchers.assertAsyncStarted(RequestResultMatchers.java:167)
    at org.springframework.test.web.servlet.result.RequestResultMatchers.lambda$asyncStarted$0(RequestResultMatchers.java:70)
    at org.springframework.test.web.servlet.MockMvc$1.andExpect(MockMvc.java:214)
    at org.springframework.test.web.servlet.result.RequestResultMatchersDsl.asyncStarted(RequestResultMatchersDsl.kt:36)
    at dev.aga.controller.SomeControllerTest.normal___async$lambda$6$lambda$5(SomeControllerTest.kt:39)
    at org.springframework.test.web.servlet.MockMvcResultMatchersDsl.request(MockMvcResultMatchersDsl.kt:34)
    at dev.aga.controller.SomeControllerTest.normal___async$lambda$6(SomeControllerTest.kt:39)
    at org.springframework.test.web.servlet.ResultActionsDsl.andExpect(ResultActionsDsl.kt:18)
    at dev.aga.controller.SomeControllerTest.normal - async(SomeControllerTest.kt:37)
    at java.base/java.lang.reflect.Method.invoke(Method.java:580)
    at java.base/java.util.ArrayList.forEach(ArrayList.java:1596)
    at java.base/java.util.ArrayList.forEach(ArrayList.java:1596)