为什么ElasticSearch不接受logstash所做的grok模式?

我有下面的grok模式,可以在logstash和kibana的grok调试器中使用。

\[%{TIMESTAMP_ISO8601:req_time}\] %{IP:client_ip} (?:%{IP:forwarded_for}|\(-\)) (?:%{QS:request}|-) %{NUMBER:response_code:int} %{WORD}:%{NUMBER:request_length:int} %{WORD}:%{NUMBER:body_bytes_sent:int} %{WORD}:(?:%{QS:http_referer}|-) %{WORD}:(?:%{QS:http_user_agent}|-) (%{WORD}:(\")?(%{NUMBER:request_time:float})(\")?)?"

我试图通过Put方法创建一个新的摄取管道,但我得到一个错误,其中包含:

    "type": "parse_exception",
    "reason": "Failed to parse content to map",
    "caused_by": {
        "type": "i_o_exception",
        "reason": "Unrecognized character escape '[' (code 91)\n at [Source: org.elasticsearch.common.bytes.BytesReference$MarkSupportingStreamInputWrapper@61326735; line: 7, column: 25]"
    }