Update javadoc for recordResponseEventWhileInBackground().

Update it to make it clear that it is valid for only
explicit intents.

Bug: 206518114
Test: treehugger
Change-Id: I94ee73bb8050f4d4d6171b7d1c7f8053b43310f1

core/java/android/app/BroadcastOptions.java

@@ -523,6 +523,8 @@ public class BroadcastOptions extends ComponentOptions {
      * Sets whether events (such as posting a notification) originating from an app after it
      * receives the broadcast while in background should be recorded as responses to the broadcast.
      *
+     * <p> Note that this will only be considered when sending explicit broadcast intents.
+     *
      * @param id ID to be used for the response events corresponding to this broadcast. If the
      *           value is {@code 0} (default), then response events will not be recorded. Otherwise,
      *           they will be recorded with the ID provided.