Changing the operational state of a PortMapping should trigger a topology update

Currently, any changes (AdminState and OperationalState) occurred in the PortMapping refreshes the topology.

However, in some specific cases, the topology isn't refreshed. For instance, when only the OperationalState of PortMapping has been modified,

A quick analysis and patch shall fix the issue.

Acceptance criteria : the code does not bring regression, associated Junit tests are provided