Add Javadoc since for headers() in Delete/Patch/Post/PutExchange

See gh-33309
Closes gh-33723

spring-web/src/main/java/org/springframework/web/service/annotation/DeleteExchange.java

@@ -62,6 +62,7 @@ public @interface DeleteExchange {
 
 	/**
 	 * Alias for {@link HttpExchange#headers()}.
+	 * @since 6.2
 	 */
 	@AliasFor(annotation = HttpExchange.class)
 	String[] headers() default {};

spring-web/src/main/java/org/springframework/web/service/annotation/PatchExchange.java

@@ -62,6 +62,7 @@ public @interface PatchExchange {
 
 	/**
 	 * Alias for {@link HttpExchange#headers()}.
+	 * @since 6.2
 	 */
 	@AliasFor(annotation = HttpExchange.class)
 	String[] headers() default {};

spring-web/src/main/java/org/springframework/web/service/annotation/PostExchange.java

@@ -62,6 +62,7 @@ public @interface PostExchange {
 
 	/**
 	 * Alias for {@link HttpExchange#headers()}.
+	 * @since 6.2
 	 */
 	@AliasFor(annotation = HttpExchange.class)
 	String[] headers() default {};

spring-web/src/main/java/org/springframework/web/service/annotation/PutExchange.java

@@ -62,6 +62,7 @@ public @interface PutExchange {
 
 	/**
 	 * Alias for {@link HttpExchange#headers()}.
+	 * @since 6.2
 	 */
 	@AliasFor(annotation = HttpExchange.class)
 	String[] headers() default {};