[Supported in the .NET Framework 4.5.1 and later versions]
Gets the activity ID on the thread that the event was written to.
Assembly: mscorlib (in mscorlib.dll)
Retrieving the value of the property accesses thread local storage. This has the following implications:
The field is valid only for the duration of the EventListener.OnEventWritten callback.
If the activity ID is changed during the callback, the activity ID returned by the property is invalid.