Redefine DefaultResourceLoader default constructor for late TCCL access

Closes gh-24957

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -58,11 +58,11 @@ public class DefaultResourceLoader implements ResourceLoader {
 	/**
 	 * Create a new DefaultResourceLoader.
 	 * <p>ClassLoader access will happen using the thread context class loader
-	 * at the time of this ResourceLoader's initialization.
+	 * at the time of actual resource access (since 5.3). For more control, pass
+	 * a specific ClassLoader to {@link #DefaultResourceLoader(ClassLoader)}.
 	 * @see java.lang.Thread#getContextClassLoader()
 	 */
 	public DefaultResourceLoader() {
-		this.classLoader = ClassUtils.getDefaultClassLoader();
 	}
 
 	/**