@HttpExchange interface does not resolve return type correctly while using with suspending methods

[xnart]

Affects: 6.0.7

@HttpExchange annotated methods works as expected for simple return types, but not for generic types. For example a function expected to return List, but HttpServiceProxy resolves it as String.

interface SuspendingService {

  @GetExchange
  suspend fun body(): List<String>
}

Here is a test case :

class HttpServiceMethodKotlinTests {

  private val EXPECTED_BODY_TYPE: ParameterizedTypeReference<*> = object : ParameterizedTypeReference<List<String>>() {}

  private val client = TestHttpClientAdapter()
  private val proxyFactory = HttpServiceProxyFactory.builder(client).build()

  @Test
  fun suspendingService(): Unit = runBlocking {
    val service = proxyFactory.createClient(SuspendingService::class.java)

    service.body()
    getVerifyClientInvocation("requestToBody", EXPECTED_BODY_TYPE)
  }

  private fun getVerifyClientInvocation(methodName: String, expectedBodyType: ParameterizedTypeReference<*>) {
    assertThat(client.invokedMethodName).isEqualTo(methodName)
    assertThat(client.bodyType).isEqualTo(expectedBodyType)
  }


  private interface SuspendingService {
    @GetExchange
    suspend fun body(): List<String>
  }
}

Result:

expected: ParameterizedTypeReference<java.util.List<? extends java.lang.String>>
 but was: ParameterizedTypeReference<class java.lang.String>

---

When you change function signature as fun body(): Mono<List<String>> it returns ParameterizedTypeReference<java.util.List<java.lang.String>> as expected.

As far as i see, Only "suspending methods" affected by it. Flows works as expected.

[xnart]

Sorry, opened it on wrong repository. Copied it to spring-projects/spring-framework#30266