getResource can throw IllegalArgumentException

Class.getResource, ClassLoader.getResource, and ClassLoader.getSystemResource will throw IllegalArgumentException if a malformed URL is provided to them.

According to its javadoc, resolveURL should return null if not resolvable, so catch the IllegalArgumentException and return null.

Closes gh-26574

spring-core/src/main/java/org/springframework/core/io/ClassPathResource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2021 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.
@@ -148,14 +148,21 @@ public class ClassPathResource extends AbstractFileResolvingResource {
 	 */
 	@Nullable
 	protected URL resolveURL() {
-		if (this.clazz != null) {
-			return this.clazz.getResource(this.path);
-		}
-		else if (this.classLoader != null) {
-			return this.classLoader.getResource(this.path);
+		try {
+			if (this.clazz != null) {
+				return this.clazz.getResource(this.path);
+			}
+			else if (this.classLoader != null) {
+				return this.classLoader.getResource(this.path);
+			}
+			else {
+				return ClassLoader.getSystemResource(this.path);
+			}
 		}
-		else {
-			return ClassLoader.getSystemResource(this.path);
+		catch (IllegalArgumentException ex) {
+			// Should not happen according to the JDK's contract:
+			// see https://github.com/openjdk/jdk/pull/2662
+			return null;
 		}
 	}