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

Author: philwebb

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/audit/AuditEvent.java

@@ -41,6 +41,7 @@
  * (wrappers for AuditEvent).
  *
  * @author Dave Syer
+ * @since 1.0.0
  * @see AuditEventRepository
  */
 @JsonInclude(Include.NON_EMPTY)

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/audit/AuditEventRepository.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2016 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 @@
  *
  * @author Dave Syer
  * @author Vedran Pavic
+ * @since 1.0.0
  */
 public interface AuditEventRepository {
 

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/audit/InMemoryAuditEventRepository.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2017 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.
@@ -28,6 +28,7 @@
  * @author Dave Syer
  * @author Phillip Webb
  * @author Vedran Pavic
+ * @since 1.0.0
  */
 public class InMemoryAuditEventRepository implements AuditEventRepository {
 

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/audit/listener/AuditApplicationEvent.java

@@ -27,6 +27,7 @@
  * Spring {@link ApplicationEvent} to encapsulate {@link AuditEvent}s.
  *
  * @author Dave Syer
+ * @since 1.0.0
  */
 public class AuditApplicationEvent extends ApplicationEvent {
 

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/audit/listener/AuditListener.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2016 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.
@@ -29,6 +29,7 @@
  * @author Dave Syer
  * @author Stephane Nicoll
  * @author Vedran Pavic
+ * @since 1.0.0
  */
 public class AuditListener extends AbstractAuditListener {
 

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/autoconfigure/ActuatorMetricWriter.java

@@ -30,6 +30,7 @@
  * distinguish it from others that might be installed by the user).
  *
  * @author Dave Syer
+ * @since 1.3.0
  */
 @Qualifier
 @Target({ ElementType.FIELD, ElementType.METHOD, ElementType.PARAMETER, ElementType.TYPE, ElementType.ANNOTATION_TYPE })

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/autoconfigure/AuditAutoConfiguration.java

@@ -37,6 +37,7 @@
  *
  * @author Dave Syer
  * @author Vedran Pavic
+ * @since 1.0.0
  */
 @Configuration
 public class AuditAutoConfiguration {

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/autoconfigure/CrshAutoConfiguration.java

@@ -114,6 +114,7 @@
  *
  * @author Christian Dupuis
  * @author Matt Benson
+ * @since 1.0.0
  * @see ShellProperties
  * @deprecated as of 1.5 since CRaSH is not actively maintained
  */

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/autoconfigure/EndpointAutoConfiguration.java

@@ -77,6 +77,7 @@
  * @author Eddú Meléndez
  * @author Meang Akira Tanaka
  * @author Ben Hale
+ * @since 1.0.0
  */
 @Configuration
 @AutoConfigureAfter({ FlywayAutoConfiguration.class, LiquibaseAutoConfiguration.class })

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/autoconfigure/EndpointMBeanExportAutoConfiguration.java

@@ -50,6 +50,7 @@
  *
  * @author Christian Dupuis
  * @author Andy Wilkinson
+ * @since 1.0.0
  */
 @Configuration
 @Conditional(JmxEnabledCondition.class)