接口地址：RoadFlow地址/RoadFlowOpenApi/FlowExecute/GetBackSteps

请求类型：POST

请求参数：

    token：通过获取token接口获取到的token字符串,

    taskId：任务id

    formData：表单数据json字符串

返回：

{

    "success":true, //是否成功

    "code":0, //0-成功 1-没有找到对应的系统，参数code或key错误

    "msg":"", //不成功时的错误信息

    "data":{ 

        //要退回的步骤

        "steps": [

            {

                allowSelect: 0,是否允许选择人员

                checked: true,//默认选中

                disabled: true,//默认禁止选择

                id: "178210457018438",步骤id

                members: "u_172355561286672"

                name: "步骤1",//步骤名称

                selectRange: "u_172355561286672",//选择范围

            }...

        ]

     }

}

示例：

       //调用api得到要退回的步骤
        $.ajax({
            url: roadflowAddress + '/RoadFlowOpenApi/FlowExecute/GetBackSteps',
            type: 'post',
            async: true,
            data: {token:'@ViewData["token"]',taskId:'@ViewData["taskId"]',formData:JSON.stringify(formData)},
            dataType: 'json',
            success: function(json){
                if(json.code != 0){
                    alert(json.msg);
                }else{
                    //得到要退回步骤
                    var steps = json.data.steps;
                    
                }
            }
        });