There is NullPointerException when remove "Animated GIF" icon and "Transparent animated GIF" icon.

Testsuite name: Awt manual
Test name(s): AWT_SystemTray/Manual/MultipleIcons
Product(s) tested: JDK 10.0.2 b05(64bit)
OS/architecture: oel7.4-uek-x64/tonga-4.0.2-rc2.jar

Actual results:
1.
1)Select "Animated GIF"(or "Transparent animated GIF") from the 'Select Image' Choice and click the 'AddIcon' button three times.

The location of the system tray icons display is different previous oel6.4,please refer to MultipleIcons_oel6.4.jpg.

The icon is displayed in the upper left corner and three black icons in the lower left corner,please refer to MultipleIcons_add.jpg.

2)Click the 'RemoveIcon' button to remove the icon,one of the black icon is removed and it throw NullPointerException,please refer to MultipleIcons_removed.jpg and out.log;

2.There is no such issue when to add and remove "GIF Image","PNG Image","JPG Image","BMP Image" or "Transparent GIF".