public int getContentAction() {
            return mContentActionIndex;
        }
Get the index of the notification action, if any, that was specified as being clickable
with the content of this notification. This action will no longer display separately
from the notification's content.

<p>For notifications with multiple pages, child pages can also have content actions
set, although the list of available actions comes from the main notification and not
from the child page's notification.

<p>If wearable specific actions were added to the main notification, this index will
apply to that list, otherwise it will apply to the regular actions list.

@return the action index or {@link #UNSET_ACTION_INDEX} if no action was selected.
android/android_framework/base/src/main/java/github/tornaco/android/thanos/core/compat/NotificationCompat.java