GET /api/v2/x509/services/{serviceUuid}/signing-policies and read the policy UUID from items[0].objInfo.uuid.
GET /api/v2/x509/services/{serviceUuid}/signing-policies
Response
Note the response shape: signing policies are returned under
response.items (not response.results), and the total is response.total. The policy UUID (not the service UUID) is what you pass as policyUuid in the next step.
