Add reflection hints for @RequestPart

Closes gh-29749

spring-web/src/test/java/org/springframework/web/bind/annotation/ControllerMappingReflectiveProcessorTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -183,6 +183,24 @@ public class ControllerMappingReflectiveProcessorTests {
 				typeHint -> assertThat(typeHint.getType()).isEqualTo(TypeReference.of(SampleController.class)));
 	}
 
+	@Test
+	void registerReflectiveHintsForMethodWithPartToConvert() throws NoSuchMethodException {
+		Method method = SampleController.class.getDeclaredMethod("postPartToConvert", Request.class);
+		processor.registerReflectionHints(hints, method);
+		assertThat(hints.typeHints()).satisfiesExactlyInAnyOrder(
+				typeHint -> assertThat(typeHint.getType()).isEqualTo(TypeReference.of(SampleController.class)),
+				typeHint -> {
+					assertThat(typeHint.getType()).isEqualTo(TypeReference.of(Request.class));
+					assertThat(typeHint.getMemberCategories()).containsExactlyInAnyOrder(
+							MemberCategory.INVOKE_DECLARED_CONSTRUCTORS,
+							MemberCategory.DECLARED_FIELDS);
+					assertThat(typeHint.methods()).satisfiesExactlyInAnyOrder(
+							hint -> assertThat(hint.getName()).isEqualTo("getMessage"),
+							hint -> assertThat(hint.getName()).isEqualTo("setMessage"));
+				},
+				typeHint -> assertThat(typeHint.getType()).isEqualTo(TypeReference.of(String.class)));
+	}
+
 	static class SampleController {
 
 		@GetMapping
@@ -225,6 +243,10 @@ public class ControllerMappingReflectiveProcessorTests {
 		void postRawHttpEntity(HttpEntity  entity) {
 		}
 
+		@PostMapping
+		void postPartToConvert(@RequestPart Request request) {
+		}
+
 	}
 
 	@RestController