code: public void fill(Graphics2D g, Shape s, boolean isRounded, boolean paintRightShadow) {
          if (isRounded) {
              fillInternalShadowRounded(g, s);
          } else {
              fillInternalShadow(g, s, paintRightShadow);
          }
      }
docs: Fill the shape with the internal shadow.
  
  @param g                the Graphics context to paint with.
  @param s                the shape to fill. This is only used for its
  bounds.
  @param isRounded {@code true} if the shape is rounded, {@code false} if
  it is rectangular.
  @param paintRightShadow {@code true} if the shape is rectangular and the
  rightmost shadow should be painted, {@code false}
  otherwise.