Unwrap Kotlin inline value classes return values

The result returned by Kotlin reflective invocation of a function
returning an inline value class is wrapped, which makes sense
from Kotlin POV but from a JVM perspective the associated value
and type should be unwrapped to be consistent with what
would happen with a reflective invocation done by Java.

This commit unwraps such result.

Closes gh-33026

spring-core/src/test/kotlin/org/springframework/core/CoroutinesUtilsTests.kt

@@ -199,6 +199,15 @@ class CoroutinesUtilsTests {
 		}
 	}
 
+	@Test
+	fun invokeSuspendingFunctionWithValueClassReturnValue() {
+		val method = CoroutinesUtilsTests::class.java.declaredMethods.first { it.name.startsWith("suspendingFunctionWithValueClassReturnValue") }
+		val mono = CoroutinesUtils.invokeSuspendingFunction(method, this, null) as Mono
+		runBlocking {
+			Assertions.assertThat(mono.awaitSingle()).isEqualTo("foo")
+		}
+	}
+
 	@Test
 	fun invokeSuspendingFunctionWithValueClassWithInitParameter() {
 		val method = CoroutinesUtilsTests::class.java.declaredMethods.first { it.name.startsWith("suspendingFunctionWithValueClassWithInit") }
@@ -310,6 +319,11 @@ class CoroutinesUtilsTests {
 		return value.value
 	}
 
+	suspend fun suspendingFunctionWithValueClassReturnValue(): ValueClass {
+		delay(1)
+		return ValueClass("foo")
+	}
+
 	suspend fun suspendingFunctionWithValueClassWithInit(value: ValueClassWithInit): String {
 		delay(1)
 		return value.value