Pattern not match error while trying to send logs to splunk through fluentd container

Question

Could someone tell me if there in anything wrong with the expression i am using in config file for the log data given below. I tried different methods but i am still getting pattern not match error.

Source config file:

<source>
  @type tail
  path /tmp/PODLOG_.*
  pos_file /tmp/podfluentd.pos
  path_key log_type
  read_from_head true
  tag "splunk.add.kkklogs"
  <parse>
    @type regexp
    expression /^\[(?<timestamp>.*)\] (?<message>.*)$/
    time_type string
    time_key timestamp
    time_format %Y-%m-%d H:%M:%S,%N
    types id:integer
    keep_time_key true
  </parse>
</source>

Log files:

[2022-03-25 05:05:37,646] WARN The configuration 'm.m.m' was supplied but isn't a known config. (org.apache.kafka.clients.producer.ProducerConfig)
[2022-03-25 05:05:37,646] INFO Kafka version: 5.5.1-ccs (org.apache.kafka.common.utils.AppInfoParser)
[2022-03-25 05:05:37,646] INFO Kafka commitId: 3c4345dfh9e87459 (org.apache.kafka.common.utils.AppInfoParser)
[2022-03-25 05:05:37,646] INFO Kafka startTimeMs: 2376374690876 (org.apache.kafka.common.utils.AppInfoParser)
[2022-03-25 05:05:37,646] INFO ConsumerConfig values: 
        allow.auto.create.topics = true
        auto.commit.interval.ms = 1000
[2022-03-25 05:05:37,656] INFO [Consumer clientId=consumer-KKK_DDD_KC-3, groupId=KKK_DDD_KC] Cluster ID: b4fvVdcYT5dkjhXolKas5w (org.apache.kafka.clients.Metadata)
[2022-03-25 05:05:37,663] INFO [Consumer clientId=consumer-KKK_DDD_KC-3, groupId=KKK_DDD_KC] Subscribed to partition(s): KKK_DDD_KC_CONFIG_B1ASD_QUAL-0 (org.apache.kafka.clients.consumer.KafkaConsumer)