CorsRegistry implements combine correctly

Closes gh-26877

spring-web/src/main/java/org/springframework/web/cors/CorsConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 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.
@@ -475,7 +475,6 @@ public class CorsConfiguration {
 	 * @return the combined {@code CorsConfiguration}, or {@code this}
 	 * configuration if the supplied configuration is {@code null}
 	 */
-	@Nullable
 	public CorsConfiguration combine(@Nullable CorsConfiguration other) {
 		if (other == null) {
 			return this;