JSON API's auto-generated "url" field on File entities is deprecated

In Drupal 8.5 core, #2825487: Fix normalization of File entities: file entities should expose the file URL as a computed property on the 'uri' base field added a computed url property to the uri field that provides the relative HTTP(S) URL for a File entity.

Until then, JSON API has included its own work-around, which added a computed url field.

For any site that was using JSON API on a version older than Drupal 8.5, JSON API will automatically keep backwards compatibility when you update to Drupal 8.5:

Drupal <8.5

…
"status":true,
"url":"/sites/default/files/llama.png",
"uuid":"…"
}

Drupal >=8.5

…
"status":true,
"url":"/sites/default/files/llama.png",
"uri":{
  "url":"/sites/default/files/llama.png",
  "value":"public/llama.png"
},
"uuid":"…"
}

You should start using uri.url rather than url.

When JSON API requires Drupal >=8.5, JSON API will remove this BC layer. JSON API will require Drupal >=8.5 when Drupal 8.6 is released.