Creating a page via API doesn't load the New Editing Experience

Issue Summary

When our instance is rolled out to the new editing experience if we create a new page or space using API, this page and space is created in the old editor and are not converted to the new editing experience when edited.

Environment

• Cloud
• New Editing Experience

Steps to Reproduce

1. Create a page via API - you can use the below curl:

   curl -i -X POST \
       -u '<email_address>:<API_TOKEN>' \
       -H 'Accept: application/json' \
       -H 'Content-Type: application/json' \
       -d '{
             "title": "<PAGE_TITLE>",
             "type": "page",
             "space": {
               "key": "<SPACEKEY>"
             },
             "status": "current",
             "body": {
               "storage": {
                 "value": "<p>Better days will come :D</p>",
                 "representation": "storage"
               }
             }
           }' \
       https://<SITE_NAME>.atlassian.net/wiki/rest/api/content 

   To create your API token, jump here

1. Go to the page you just created;
2. It is with the old editor, try to edit it.
   And
3. Create a space via API - you can use the below curl:

   curl --user someUser@myDomain.com:apiTokenHere -
   -request POST --url 'https://<SITE_NAME>.atlassian.net/wiki/rest/api/space' 
   --header 'Accept: application/json' 
   --header 'Content-Type: application/json' 
    --data '{"key":"ACS","name": "API Created Space","description": {"plain": {"value": "someValue","representation": "someRepresentation"}}}'
   

   Expected Results

When accessing the page/space overview page, the published version should be already in the new editor, but even editing it, the page should be converted to the new editing experience.

Actual Results

The pages is with the old editor and doesn't get converted.

Workaround

It's possible to simply add the following metadata to the request's payload, so the page will be created using the new editor:

"metadata": {
    "properties": {
        "editor": {
            "key": "editor",
            "value": "v2"
        }
    }
}

Here's a complete example;

fetch("https://INSTANCE.atlassian.net/wiki/rest/api/content", {
    "credentials": "include",
    "headers": {
        "content-type": "application/json",
    },
    "body": `{
		"title": "Test new page (API)",
		"type":"page",
		"status":"current",
		"space":{
			"key":"TS"
		},
		"body": {
			"storage": {
				"value": "<p>Created through the REST API</p>",
				"representation": "storage"
			}
		},
		"metadata": {
        		"properties": {
          			"editor": {
            				"key": "editor",
            				"value": "v2"
          			}
        		}
      		}
	}`,
    "method": "POST",
});