es 脚本排序 script_parse_exception

jar包版本：5.6.0

代码片段：
SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
Script script = new Script("7 == doc['sortStatus'].value && 6 == doc['sortStatus'].value ? '1' : '0'");
ScriptSortBuilder order = new ScriptSortBuilder(script, NUMBER).order(SortOrder.DESC);
searchSourceBuilder.sort(order);

错误信息：
{"error":{"root_cause":[{"type":"script_parse_exception","reason":"unexpected field [source]"}],"type":"search_phase_execution_exception","reason":"all shards failed","phase":"query","grouped":true,"failed_shards":[{"shard":0,"index":"owhat","node":"3YNiUcFRRMCi5EH04LnrXA","reason":{"type":"script_parse_exception","reason":"unexpected field [source]"}}]},"status":500}

实际执行脚本：
{
"from": 0,
"size": 10,
"sort": [
{
"_script": {
"script": {
"source": "7 == doc['sortStatus'].value && 6 == doc['sortStatus'].value ? 1 : 0",
"lang": "painless"
},
"type": "number",
"order": "desc"
}
}
]
}

现象：
直接引用脚本符合查询可以正常查询结果，代码执行不可以