fix 'runtime' property type in DynamicTemplate class

[fbaligand]

Currently, in DynamicTemplate class, the "runtime" property has "Property" type.
This PR aims to fix that by referencing "RuntimeField" type.

[pquentin]

This seems correct to me. We don't have any YAML tests on this, only Java tests (that should probably have been YAML tests.) runtime, like mapping is parsed as a Map<String, Object>, which isn't helpful:

https://github.com/elastic/elasticsearch/blob/1e8262170ed339d8f2ebdc6de6fd581adb40096d/server/src/main/java/org/elasticsearch/index/mapper/DynamicTemplate.java#L293-L301

But there's a unit test that shows that runtime is parsed as RuntimeField:

https://github.com/elastic/elasticsearch/blob/1e8262170ed339d8f2ebdc6de6fd581adb40096d/server/src/test/java/org/elasticsearch/index/mapper/DynamicTemplatesTests.java#L609-L642

This is what the mappings look like in JSON:

"dynamic_templates": [
  {
    "my_template": {
      "match_mapping_type": "*",
      "runtime": {
        "type": "{dynamic_type}",
        "foo": "bar"
      }
    }
  }
]

And the error is unknown parameter [foo] on runtime field [__dynamic__my_template] of type [date] which is raised by the RuntimeField class:

https://github.com/elastic/elasticsearch/blob/1e8262170ed339d8f2ebdc6de6fd581adb40096d/server/src/main/java/org/elasticsearch/index/mapper/RuntimeField.java#L82-L86

LGTM!

[fbaligand]

Thanks for the merge @pquentin !

[pquentin]

Merci pour la contribution !

This will be released in version 8.18 and above of the Elasticsearch clients.

[fbaligand]

Super!