code: @NonNull
      public IconicsDrawable shadowPx(
              @Dimension(unit = PX) float radius,
              @Dimension(unit = PX) float dx,
              @Dimension(unit = PX) float dy,
              @ColorInt int color) {
          mShadowRadius = radius;
          mShadowDx = dx;
          mShadowDy = dy;
          mShadowColor = color;
  
          mIconBrush.getPaint().setShadowLayer(radius, dx, dy, color);
          invalidateSelf();
          return this;
      }
docs: Sets the shadow for the icon
  This requires shadow support to be enabled on the view holding this `IconicsDrawable`
  
  @return The current IconicsDrawable for chaining.
  @see Paint#setShadowLayer(float, float, float, int)
  @see #enableShadowSupport(View)