Fix checkstyle issues

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/UnknownHttpStatusCodeException.java

@@ -1,3 +1,19 @@
+/*
+ * Copyright 2002-2018 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package org.springframework.web.reactive.function.client;
 
 import java.nio.charset.Charset;
@@ -19,5 +35,5 @@ public class UnknownHttpStatusCodeException extends WebClientResponseException {
 		super("Unknown status code [" + statusCode + "]", statusCode, "",
 				headers, responseBody, responseCharset);
 	}
-	
+
 }