Fix Javadoc @Since checkstle violations

Apply consistent `@Since` tags and retrofit the existing code using a
best guess from the git history.

Closes gh-17360

spring-boot-integration-tests/spring-boot-configuration-processor-tests/src/main/java/sample/AnnotatedSample.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2018 the original author or authors.
+ * Copyright 2012-2019 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.
@@ -24,6 +24,7 @@ import org.springframework.boot.context.properties.ConfigurationProperties;
  * Test that a valid type is generated if an annotation is present.
  *
  * @author Stephane Nicoll
+ * @since 1.5.10
  */
 @ConfigurationProperties("annotated")
 public class AnnotatedSample {