Polish "Suppress debug log output during Logback initialization"

See gh-12071

spring-boot/src/main/java/org/springframework/boot/logging/logback/LogbackLoggingSystem.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.

spring-boot/src/test/java/org/springframework/boot/logging/logback/LogbackLoggingSystemTests.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -137,7 +137,7 @@ public class LogbackLoggingSystemTests extends AbstractLoggingSystemTests {
 	}
 
 	@Test
-	public void testNonDefaultConfigLocation() throws Exception {
+	public void testNonDefaultConfigLocation() {
 		int existingOutputLength = this.output.toString().length();
 		this.loggingSystem.beforeInitialize();
 		this.loggingSystem.initialize(this.initializationContext,