Missing key_type feature on 0.10

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Description

On 0.10, key_type still exists from 0.9 but is not manage.

Indeed, ResourceIdentity only handles primary key. It might work if key_type is actually the primary key but it's not. Errors are raising.

For example, with id as a primary key and uuid as key_type.

This is a part of the job. I'm not 100% confident with all side effects that update might have. Maybe @lgebhardt can help with his knowledge.

Gitter on 11th of December 2020

Beginne mit dem Lesen von ResourceIdentity in Version 0.10 und vergleiche, wie key_type in 0.9 existierte. Reproduziere das Beispiel mit id als Primärschlüssel und uuid als key_type, verfolge dann die Fehler und mögliche Nebenwirkungen von Updates. Abgeschlossen ist die Aufgabe, wenn key_type ohne diese Fehler verarbeitet wird und das beabsichtigte Verhalten bestätigt ist.