Primefaces dynamic menu icon not showing

问题

Im creating my menu intiarly with help of java. Now im trying to set an icon, but it doesn't show.

Here is my css class:

    .qualiteatsmanager {
    background: url("/resources/images/icons/qm.png") !important;
    height:16px;
    width: 16px;
}

Im setting the icon like this: studentMenuItem.setIcon("qualiteatsmanager");.

but the menu only shows the standard ui-icon-carat-1-n.

The images can be found under src/main/java/../resources/images/icons.

来源：https://stackoverflow.com/questions/30695332/primefaces-dynamic-menu-icon-not-showing