[ISSUE] User update incorrectly says user_name is optional

[oliverbeagley-pgg]

Description
On v0.53.0 When trying to remove entitlements from users I get the following error: databricks.sdk.errors.platform.BadRequest: invalidValue Required attribute userName is missing in the SCIM Object.

When I fix that I get errors about group attributes not being updated, so I think .update() may be fairly broken in general and/or poorly documented.

Reproduction

from databricks.sdk import WorkspaceClient

wc = WorkspaceClient()

users_with_entitlements = (
    user for user in wc.users.list() if len(user.entitlements) > 0
)

for user in users_with_entitlements:
    wc.users.update(id=user.id, entitlements=[])

Traceback

Traceback (most recent call last):
  File "/tmp/tmp.MJoJmb501l/dbr.py", line 15, in <module>
    wc.users.update(id=user.id, entitlements=[])
    ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/tmp/tmp.MJoJmb501l/.venv/lib/python3.13/site-packages/databricks/sdk/service/iam.py", line 4397, in update
    self._api.do("PUT", f"/api/2.0/preview/scim/v2/Users/{id}", body=body, headers=headers)
    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/tmp/tmp.MJoJmb501l/.venv/lib/python3.13/site-packages/databricks/sdk/core.py", line 85, in do
    return self._api_client.do(
           ~~~~~~~~~~~~~~~~~~~^
        method=method,
        ^^^^^^^^^^^^^^
    ...<8 lines>...
        response_headers=response_headers,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/tmp/tmp.MJoJmb501l/.venv/lib/python3.13/site-packages/databricks/sdk/_base_client.py", line 196, in do
    response = call(
        method,
    ...<7 lines>...
        auth=auth,
    )
  File "/tmp/tmp.MJoJmb501l/.venv/lib/python3.13/site-packages/databricks/sdk/retries.py", line 57, in wrapper
    raise err
  File "/tmp/tmp.MJoJmb501l/.venv/lib/python3.13/site-packages/databricks/sdk/retries.py", line 36, in wrapper
    return func(*args, **kwargs)
  File "/tmp/tmp.MJoJmb501l/.venv/lib/python3.13/site-packages/databricks/sdk/_base_client.py", line 298, in _perform
    raise error from None
databricks.sdk.errors.platform.BadRequest: invalidValue Required attribute userName is missing in the SCIM Object.

Expected behavior
Not needing to specify user_name if it is truly optional. Type system validation

Other Information

• OS: ubuntu
• Version: 0.53.0