Polish contribution

See gh-26871

spring-context/src/main/java/org/springframework/context/ApplicationEvent.java

 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2021 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.
@@ -38,9 +38,11 @@ public abstract class ApplicationEvent extends EventObject {
 
 
 	/**
-	 * Create a new {@code ApplicationEvent}.
+	 * Create a new {@code ApplicationEvent} with its {@link #getTimestamp() timestamp}
+	 * set to {@link System#currentTimeMillis()}.
 	 * @param source the object on which the event initially occurred or with
 	 * which the event is associated (never {@code null})
+	 * @see #ApplicationEvent(Object, Clock)
 	 */
 	public ApplicationEvent(Object source) {
 		super(source);
@@ -48,10 +50,14 @@ public abstract class ApplicationEvent extends EventObject {
 	}
 
 	/**
-	 * Create a new {@code ApplicationEvent} with a fixed timestamp.
+	 * Create a new {@code ApplicationEvent} with its {@link #getTimestamp() timestamp}
+	 * set to the value returned by {@link Clock#millis()} in the provided {@link Clock}.
+	 * <p>This constructor is typically used in testing scenarios.
 	 * @param source the object on which the event initially occurred or with
 	 * which the event is associated (never {@code null})
 	 * @param clock a clock which will provide the timestamp
+	 * @since 5.3.8
+	 * @see #ApplicationEvent(Object)
 	 */
 	public ApplicationEvent(Object source, Clock clock) {
 		super(source);
@@ -60,7 +66,9 @@ public abstract class ApplicationEvent extends EventObject {
 
 
 	/**
-	 * Return the system time in milliseconds when the event occurred.
+	 * Return the time in milliseconds when the event occurred.
+	 * @see #ApplicationEvent(Object)
+	 * @see #ApplicationEvent(Object, Clock)
 	 */
 	public final long getTimestamp() {
 		return this.timestamp;