public sealed class NoTopologyProperties : TopologyProperties 

// Retrieves the properties of the active topology associated with the specified map asynchronously.
var activeTopologyProperties = await activeMap.GetActiveTopologyAsync();
var isMapTopology = activeTopologyProperties is MapTopologyProperties;
var isGdbTopology = activeTopologyProperties is GeodatabaseTopologyProperties;
var isNoTopology = activeTopologyProperties is NoTopologyProperties;