The optional default maximum duration for tasks of an activity type specified when registering the activity type. You can override this
default when scheduling a task through the ScheduleActivityTaskDecision. The valid values are integers greater than or equal
to 0. An integer value can be used to specify the duration in seconds while NONE can be used to specify unlimited duration.
Constraints:

C# |
public string DefaultTaskStartToCloseTimeout { get; set; }