private static int getBorderCornerRadius( Component owner, Component contents ) {
		String uiKey =
			(contents instanceof BasicComboPopup) ? "ComboBox.borderCornerRadius" :
			(contents instanceof JPopupMenu) ? "PopupMenu.borderCornerRadius" :
			(contents instanceof JToolTip) ? "ToolTip.borderCornerRadius" :
			"Popup.borderCornerRadius";

		Object value = getOption( owner, contents, FlatClientProperties.POPUP_BORDER_CORNER_RADIUS, uiKey );
		return (value instanceof Integer) ? (Integer) value : 0;
	}
Checks whether the owner component returns a tooltip location in
JComponent.getToolTipLocation(MouseEvent).
flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatPopupFactory.java