`canvas.api.layout.post` routes missing `_format: 'json'` requirement
>>> [!note] Migrated issue
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<!-- Migrated from issue #3558747. -->
Reported by: [attilatilman](https://www.drupal.org/user/3528404)
Related to !338
>>>
<h3 id="overview">Overview</h3>
<p>Update `canvas.api.layout.post: &layout_post_route` in canvas.routing.yml to have `_format: 'json'` as a requirement.</p>
issue