public WearableExtender setContentAction(int actionIndex) {
            mContentActionIndex = actionIndex;
            return this;
        }
Set an action from this notification's actions to be 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.

@param actionIndex The index of the action to hoist onto the current notification page.
                   If wearable actions were added to the main notification, this index
                   will apply to that list, otherwise it will apply to the regular
                   actions list.
android/android_framework/base/src/main/java/github/tornaco/android/thanos/core/compat/NotificationCompat.java