Unwrap Optional for @RequestParam reverse resolution

Closes gh-22656

spring-web/src/main/java/org/springframework/web/method/annotation/RequestParamMethodArgumentResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -20,6 +20,7 @@ import java.beans.PropertyEditor;
 import java.util.Collection;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.Part;
 
@@ -217,6 +218,11 @@ public class RequestParamMethodArgumentResolver extends AbstractNamedValueMethod
 				parameter.getParameterName() : requestParam.name());
 		Assert.state(name != null, "Unresolvable parameter name");
 
+		parameter = parameter.nestedIfOptional();
+		if (value instanceof Optional) {
+			value = ((Optional<?>) value).orElse(null);
+		}
+
 		if (value == null) {
 			if (requestParam != null &&
 					(!requestParam.required() || !requestParam.defaultValue().equals(ValueConstants.DEFAULT_NONE))) {

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/MvcUriComponentsBuilderTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2018 the original author or authors.
+ * Copyright 2012-2019 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.
@@ -23,6 +23,7 @@ import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Optional;
 import javax.servlet.http.HttpServletRequest;
 
 import org.hamcrest.Matchers;
@@ -264,6 +265,15 @@ public class MvcUriComponentsBuilderTests {
 		assertThat(uriComponents.toUriString(), is("http://localhost/something/optional-param"));
 	}
 
+	@Test  // gh-22656
+	public void fromMethodNameWithOptionalNamedParam() {
+		UriComponents uriComponents = fromMethodName(ControllerWithMethods.class,
+				"methodWithOptionalNamedParam", Optional.of("foo")).build();
+
+		assertThat(uriComponents.toUriString(),
+				is("http://localhost/something/optional-param-with-name?search=foo"));
+	}
+
 	@Test
 	public void fromMethodNameWithMetaAnnotation() {
 		UriComponents uriComponents = fromMethodName(MetaAnnotationController.class, "handleInput").build();
@@ -533,6 +543,11 @@ public class MvcUriComponentsBuilderTests {
 		HttpEntity<Void> methodWithOptionalParam(@RequestParam(defaultValue = "") String q) {
 			return null;
 		}
+
+		@GetMapping("/optional-param-with-name")
+		HttpEntity<Void> methodWithOptionalNamedParam(@RequestParam("search") Optional<String> q) {
+			return null;
+		}
 	}