标记空值echarts 折线配置项内容和展示

如图，x轴为9,10的值为null，如何在x轴上显示坐标点但是不连线？

      option = {
    toolbox: {
        show : false,
    },
    xAxis : [
        {
            show : false,
            type : 'category',
            data : ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '10']
        }
    ],
    yAxis : [
        {
            show : false,
            type : 'value',
        }
    ],
    calculable : true,
    tooltip : {
        trigger: 'axis',
        formatter: "{b}时 : {c}次"
    },
    series : [
        {
            name:'test1',
            type:'line',
            connectNulls: false,
            itemStyle: {
                normal: {
                    lineStyle: {
                        shadowColor : 'rgba(0,0,0,0.4)'
                    }
                }
            },
            data:[0, 0, 0, 0, 0, 0, 14, 3, 0, null,null]
        },
        
        {
            name: 'test1',
            type: 'scatter',
            data: [0, 0, 0, 0, 0, 0, '-','-','-','-'],
            itemStyle: {
                normal: {
                    color: 'grey',
                    opacity:'1'
                }
    
            }
            
        }
    ]
};