function mergeAvailabilityWithParent(child) {
  const parent = child.parent;
  if (defined(parent)) {
    const parentAvailability = parent.availability;
    if (defined(parentAvailability)) {
      const childAvailability = child.availability;
      if (defined(childAvailability)) {
        childAvailability.intersect(parentAvailability);
      } else {
        child.availability = parentAvailability;
      }
    }
  }
}
Cleans up any non-entity elements created by the data source. Currently this only affects ScreenOverlay elements.