Merge pull request #13197 from izeye:polish-20180517-2nd

* pr/13197:
  Make ErrorProperties.whitelabel final

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/ErrorProperties.java

@@ -44,7 +44,7 @@ public class ErrorProperties {
 	 */
 	private IncludeStacktrace includeStacktrace = IncludeStacktrace.NEVER;
 
-	private Whitelabel whitelabel = new Whitelabel();
+	private final Whitelabel whitelabel = new Whitelabel();
 
 	public String getPath() {
 		return this.path;
@@ -74,10 +74,6 @@ public class ErrorProperties {
 		return this.whitelabel;
 	}
 
-	public void setWhitelabel(Whitelabel whitelabel) {
-		this.whitelabel = whitelabel;
-	}
-
 	/**
 	 * Include Stacktrace attribute options.
 	 */