Add support for @RequestMapping on Kotlin property accessors

This commit refines InvocableHandlerMethod (both Servlet and
Reactive variants) in order to support annotated property
accessors as they translate into regular Java methods, instead
of throwing a NullPointerException.

Closes gh-31856

spring-web/src/test/kotlin/org/springframework/web/method/support/InvocableHandlerMethodKotlinTests.kt

@@ -98,6 +98,12 @@ class InvocableHandlerMethodKotlinTests {
 		Assertions.assertThat(value).isEqualTo(3.1)
 	}
 
+	@Test
+	fun propertyAccessor() {
+		val value = getInvocable(PropertyAccessorHandler::class.java).invokeForRequest(request, null)
+		Assertions.assertThat(value).isEqualTo("foo")
+	}
+
 	private fun getInvocable(clazz: Class<*>, vararg argTypes: Class<*>): InvocableHandlerMethod {
 		val method = ResolvableMethod.on(clazz).argTypes(*argTypes).resolveMethod()
 		val handlerMethod = InvocableHandlerMethod(clazz.constructors.first().newInstance(), method)
@@ -138,6 +144,12 @@ class InvocableHandlerMethodKotlinTests {
 			limit.value
 	}
 
+	private class PropertyAccessorHandler {
+
+		val prop: String
+			get() = "foo"
+	}
+
 	@JvmInline
 	value class LongValueClass(val value: Long)