private static Insets nonNegativeInsets( Insets shadowInsets ) {
		return new Insets( Math.max( shadowInsets.top, 0 ), Math.max( shadowInsets.left, 0 ),
			Math.max( shadowInsets.bottom, 0 ), Math.max( shadowInsets.right, 0 ) );
	}
Paints a drop shadow border around the component.
Supports 1-sided, 2-side, 3-sided or 4-sided drop shadows.
<p>
The shadow insets allow specifying drop shadow thickness for each side.
A zero or negative value hides the drop shadow on that side.
A negative value can be used to indent the drop shadow on corners.
E.g. -4 on left indents drop shadow at top-left and bottom-left corners by 4 pixels.

@author Karl Tauber
flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatDropShadowBorder.java