code: public <T> void setItems(@NonNull List<T> items) {
      adapter = new MaterialSpinnerAdapter<>(getContext(), items)
          .setPopupPadding(popupPaddingLeft, popupPaddingTop, popupPaddingRight, popupPaddingBottom)
          .setBackgroundSelector(backgroundSelector)
          .setTextColor(textColor);
      setAdapterInternal(adapter);
    }
docs: Set the dropdown items
  
  @param items A list of items
  @param <T> The item type