Enforce cleaned URL for root resource from ClassLoader

Closes gh-32828

Author: jhoeller

spring-core/src/main/java/org/springframework/core/io/support/PathMatchingResourcePatternResolver.java

@@ -423,6 +423,17 @@ protected Resource convertClassLoaderURL(URL url) {
 }
 }
 else {
+String urlString = url.toString();
+String cleanedPath = StringUtils.cleanPath(urlString);
+if (!cleanedPath.equals(urlString)) {
+// Prefer cleaned URL, aligned with UrlResource#createRelative(String)
+try {
+return new UrlResource(ResourceUtils.toURI(cleanedPath));
+}
+catch (URISyntaxException | MalformedURLException ex) {
+// Fallback to regular URL construction below...
+}
+}
 return new UrlResource(url);
 }
 }