Make assertion message lazy in ServletRequestPathUtils

Closes gh-27946

Author: bclozel

spring-web/src/main/java/org/springframework/web/util/ServletRequestPathUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -74,7 +74,7 @@ public static RequestPath parseAndCache(HttpServletRequest request) {
 	 */
 	public static RequestPath getParsedRequestPath(ServletRequest request) {
 		RequestPath path = (RequestPath) request.getAttribute(PATH_ATTRIBUTE);
-		Assert.notNull(path, "Expected parsed RequestPath in request attribute \"" + PATH_ATTRIBUTE + "\".");
+		Assert.notNull(path, () -> "Expected parsed RequestPath in request attribute \"" + PATH_ATTRIBUTE + "\".");
 		return path;
 	}