Currently only MS Exchange Server 2016 CU1 to CU10 is supported.
The support for MS Exchange Server 2016 CU11 is targeted for the release of MS Exchange Server plug-in 12.2
which as per current planning will also incorporate support for MS Exchange Server 2019.
To conform the inclusion of these two versions of exchange are supported in exchange plugin 12.2 please check release notes when version12.2 is available.