Section <templates> is not used in <match **> of opensearch plugin

[ng-bsy]

• read the contribution guideline
• (optional) already reported 3rd party upstream repository or mailing list if you use k8s addon or helm charts.

Steps to replicate

- match:
    $tag: '**'
    $type: opensearch
    scheme: https
    ssl_verify: false
    hosts: oshost01,oshost02
    user: XXXX
    password: XXXX
    logstash_format: false
    index_name: fluentd.${tag}
    templates:
      fluentd: '/etc/fluent/os_index_templates/fluentd.json'

[warn]: section <templates> is not used in <match **> of opensearch plugin

Expected Behavior or What you need to ask

I expect to not read the warning message and the opensearch plugin to use the provided templates

Using Fluentd and OpenSearch plugin versions

• Ubuntu 22.04 LTS
• Docker fluentd:v1.16-1
• fluentd 1.16.2
• fluent-plugin-opensearch 1.1.4
• OpenSearch version 2.5
• OpenSearch template

{
  "index_patterns" : [
    "fluentd.*"
  ],
  "priority": 10,
  "data_stream": {}
}

[ng-bsy]

Okay, I suppose this one can be closed.
It's documented here: https://docs.fluentd.org/configuration/config-file-yaml#special-yaml-elements

templates:
      fluentd: '/etc/fluent/os_index_templates/fluentd.json'

has to be replaced with

templates:  !fluent/json {fluentd: '/etc/fluent/os_index_templates/fluentd.json'}