🐛 400 when modifying a user with a space in username

To reproduce :

Create a user with a space in its username "example "
Modify it via a PUT request
You should get a 400 "Path id exaple doesn't match with body id example "
because the url is trimmed from the ending space

This username should be accepted and the request go well instead

Start from the user modification flow that sends the PUT request and reproduce the case with a username ending in a space. Trace how the username becomes the URL path and compare it with the request body; done means the update succeeds without the 400 path/body mismatch.

Written by the indexing model from the issue text.