freemarker判断对象是否为空

<#escape x as jsonUtils.encodeJSONString(x)>
{
   "items":
    [
        <#list searchresult.items as item>
        {
          "nodeRef": "${item.nodeRef}",
            "docname": "${item.name!‘‘}",
            "read":"${(item.properties.hits)!‘0‘}"
        }<#if item_has_next>,</#if>
        </#list>
    ]
}
</#escape>