How to forward the local port of a SpringBootTest to a test configuration

I am currently struggling with the server port injection of the SpringBootTest instance. I've written a test configuration class where I would like to access this port.

Test Configuration class:

@Target(AnnotationTarget.CLASS, AnnotationTarget.FILE)
@Retention(AnnotationRetention.RUNTIME)
@Import(value = [TestTemplateConfig::class])
annotation class TestAnnotation

@Configuration
open class TestTemplateConfig {
    @Value("\${server.port}")
    private var localPort: Int? = null

    @Bean
    open fun foo() = Foo(localPort)
}

The Test looks like this:

@SpringBootJunit5Test
@TestAnnotation
@EnableTestCouchbase
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
class MyIntegrationTest {
    @LocalServerPort
    var port: Int = 0

    @Autowired
    private lateinit var foo: Foo

    ...
}

The problem now is, that I always receive a value of zero for the port in the configuration class. Because I don't get null this sounds like it is working to get the port but the wrong one (I think zero is defined for a random port in spring). The evaluation of the server port in the MyIntegrationTest class is working properly so far.

Any ideas to fix this?

Thanks

Here's what we did in this case:

@Configuration
class Config {
    private lateinit var port: java.lang.Integer // declare a var to store the port
    
    @EventListener // subscribe to servlet container initialized event
    fun onServletContainerInitialized(event: EmbeddedServletContainerInitializedEvent) {
        port = event.embeddedServletContainer.port // when event is fired, extract the port for that event
    }
}