graph类的图表怎么画出自环echarts graph配置项内容和展示

source和target如果一样的话就什么都画不出来了，不能画出图论的那种自环。以后会加自环功能吗？还是我没找到画自环的选项？

      option = {
    title: {
        text: 'Awesome Chart'
    },
    series: [{
        type: 'graph',
        layout:'force',
        data:[{name:"1", x:-50, y:10, value:100}, {name:"2", x:50, y:10, value:100}],
        links:[{source:"1", target:"1",value:100},{source:"1", target:"2",value:100}]
    }]
};