[ISSUE] ZPA update_isolation_rule / update_isolation_rule_v2 raise AttributeError on a partial update (unguarded action.upper())

[hackerboey]

Description

PolicySetControllerAPI.update_isolation_rule and update_isolation_rule_v2 both declare
action: str = None, but build their payload with an unguarded action.upper()
(zscaler/zpa/policies.py:1308 and :2523 on master e7f5f7e). Omitting action — as you
would for a partial update — raises before any request is made, so those two methods cannot do
a partial update at all.

Sibling update methods in the same file already guard this, e.g. update_access_rule
(policies.py:695) uses "action": action.upper() if action else None, so this looks like an
oversight rather than intent.

Reproduction

No credentials needed — the request executor is mocked, so the failure happens while building
the payload:

from unittest.mock import Mock
from zscaler.zpa.policies import PolicySetControllerAPI

policy_set = Mock()
policy_set.get_body.return_value = {"id": "72058304855090130"}

executor = Mock()
executor.create_request.return_value = ({}, None)
executor.execute.side_effect = [(policy_set, None), (None, None)]

api = PolicySetControllerAPI(executor, {"client": {"customerId": "72058304855090128"}})

# Partial update: change only the description, leave action untouched.
api.update_isolation_rule_v2(rule_id="72058304855090129", description="partial update")

The equivalent real call is
client.zpa.policies.update_isolation_rule_v2(rule_id="72058304855090129", description="partial update").
update_isolation_rule (v1) fails the same way.

Expected behavior

The update request is sent with the fields that were supplied, the same as
update_access_rule_v2 / update_client_forwarding_rule_v2 already do when action is omitted.

Actual behavior

  File ".../zscaler/zpa/policies.py", line 2523, in update_isolation_rule_v2
    "action": action.upper(),
              ^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'upper'

Other Information

• SDK version: 1.9.44 (master e7f5f7e)
• Python 3.12
• A PR is attached: it applies the existing action.upper() if action else None guard to both
  sites and adds a unit test covering the partial-update path.