无法在jointjs中更改UML状态的颜色

var umlState = new joint.shapes.uml.State({
    position: { x: 100, y: 100 },
    size: { width: 200, height: 100 },
    attrs: {
        '.uml-state-name': { text: 'State Name' },
        '.uml-state-body': { fill: '#F9F9F9', stroke: '#000000' },
        '.uml-state-separator': { stroke: '#000000' }
    }
});

umlState.on('change:attrs', function(element, attrs) {
    var stateColor = attrs['.uml-state-color'];
    // 根据状态颜色更新背景颜色和边框颜色
    element.attr('.uml-state-body/fill', stateColor);
    element.attr('.uml-state-body/stroke', stateColor);
});