We are trying to set a specific user_id in a pre-registration hook. But each time the id of the created user is overwritten by an id generated by Auth0. How could we keep the user_id we set ?
We tried the following options : user.id = 'xxx' / user.user_id = 'xxx' / response.user.user_id = 'xxx' / response.user.id = 'xxx'

Symptoms

Custom user_id cannot be set by pre-registration hook.

• User ID 
• Pre-Registration Hook

Unsupported feature.

• https://auth0.com/docs/get-started/apis/scopes/sample-use-cases-scopes-and-claims#add-custom-claims-to-a-token

• https://auth0.com/docs/manage-users/user-accounts/metadata/metadata-fields-data#name-collision