Istio changed the registry datatype for ExportTo between Istio 1.18 and 1.20.  This causes a problem for v1.73, which is being used as the Kiali version for both OSSM 2.5 (1.18) and OSSM 2.6 (1.20).

Currently, OSSM 2.5 is fine because v1.73 is using the older datatype.  But 2.6 has a problem (in the service_entry graph appender).

Changing the datatype to be compatible with Istio 1.20 would solve the issue for 2.6, but introduce an issue in 2.5.

We need to investigate whether we can add some custom marshaling to solve the problem for both versions.  If not we will likely need to fix 2.6, and then 2.5 users would need to update to get around the problem (or remove the explicit use of ExportTo in service entry definitions).