GraphicsLayer图层如何加入图例中，求解，谢谢！！！

// GraphicsLayer
                incidentsGraphicsLayer = new GraphicsLayer();
                var incidentPointSymbol = new SimpleMarkerSymbol(
                    SimpleMarkerSymbol.STYLE_CIRCLE,
                    30,
                    new SimpleLineSymbol(
                        SimpleLineSymbol.STYLE_SOLID,
                        new Color([89,95,35]), 2
                    ),
                    new Color([255,0,0,1])
                );
                var incidentsRenderer = new SimpleRenderer(incidentPointSymbol);
                incidentsGraphicsLayer.setRenderer(incidentsRenderer);
                map.addLayer(incidentsGraphicsLayer);
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上面的incidentsGraphicsLayer图层如何加入到图例中，

var legend = new Legend({
                        map: map,
                        layerInfos: [
                            
                    ]
                    }, "legendDiv");
                    legend.startup();
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谢谢了！！！！