code: private void initializeNoxItemPlaceholder(TypedArray attributes) {
      Drawable placeholder = attributes.getDrawable(R.styleable.nox_item_placeholder);
      if (placeholder == null) {
        placeholder = getContext().getResources().getDrawable(R.drawable.ic_nox);
      }
      noxConfig.setPlaceholder(placeholder);
    }
docs: Configures the placeholder used if there is no another placeholder configured in the NoxItem
  instances during the onDraw execution.