运行弹性搜索无痛脚本时，根映射定义具有不受支持的参数mapper_parsing_exception

如何解决运行弹性搜索无痛脚本时，根映射定义具有不受支持的参数mapper_parsing_exception

{
    "query": {
        "match_all": {}
    },"script": {
        "source":"if(ctx._source.containsKey('priority')){if (ctx._source.priority != null && ctx._source.priority != 'null') { ctx._source.priority_filter  =  String.valueOf(ctx._source.priority) } else { ctx._source.priority_filter = ''}}","lang": "painless"
        
    }
}

当我尝试运行上述脚本时出现以下错误，谁能告诉我哪里出错了，我的弹性搜索版本是 v6.5.2

{
        "error": {
            "root_cause": [
                {
                    "type": "mapper_parsing_exception","reason": "Root mapping deFinition has unsupported parameters:  [query : {match_all={}}] [script : {source=if(ctx._source.containsKey('priority')){if (ctx._source.priority != null && ctx._source.priority != 'null') { ctx._source.priority_filter  =  String.valueOf(ctx._source.priority) } else { ctx._source.priority_filter = ''}},lang=painless}]"
                }
            ],"type": "mapper_parsing_exception",lang=painless}]"
        },"status": 400
    }