Partial Patch Clears Omitted Fields

An endpoint documented as a partial update (PATCH) rebuilds one nested object from the request body alone, so any field the caller leaves out is written as empty or default instead of keeping its saved value — PATCH behaves like PUT.

A client PATCHes only the phone number; the server rebuilds the whole address object from the body and the saved street becomes null.

The field is missing from the request, not sent back empty; not a form that saves an inherited default as an explicit value (Untouched default becomes a permanent override).