public Builder addAction(int icon, CharSequence title, PendingIntent intent) {
            mActions.add(new Action(icon, title, intent));
            return this;
        }
Add an action to this notification. Actions are typically displayed by
the system as a button adjacent to the notification content.
<br>
Action buttons won't appear on platforms prior to Android 4.1. Action
buttons depend on expanded notifications, which are only available in Android 4.1
and later. To ensure that an action button's functionality is always available, first
implement the functionality in the {@link Activity} that starts when a user
clicks the  notification (see {@link #setContentIntent setContentIntent()}), and then
enhance the notification by implementing the same functionality with
{@link #addAction addAction()}.

@param icon   Resource ID of a drawable that represents the action.
@param title  Text describing the action.
@param intent {@link PendingIntent} to be fired when the action is invoked.
android/android_framework/base/src/main/java/github/tornaco/android/thanos/core/compat/NotificationCompat.java