Service Mesh has been removed in 2.9 and above Ops Man UI, so if you enabled it, and added a certificate and private key for Istio router, that will still remain there.
Because of that, when that cert is close to expire, Ops Man will warn you about that showing that a cert with property_reference ".properties.istio_frontend_tls_keypairs[0].certificate" will expire sin some days.
Before upgrading to Ops Man 2.11, Service Mesh needs to be removed as explained in our
docs and as instructed in this
KB article. That KB article doesn't explain how to remove the cert hence we created this one.