code: @NonNull
    @SuppressWarnings("WeakerAccess")
    public SnackbarWrapper setIcon(@DrawableRes int icon) {
      return setIcon(ContextCompat.getDrawable(context, icon));
    }
docs: Set the icon at the start of the Snackbar.  If there is no icon it will be added, or if there is then it will be
  replaced.
  
  @param icon The icon drawable resource to display.
  @return This instance.