You would not be able to directly use the task key but there are several other criteria to retrieve specifc tasks. You can refer the TaskFilterSpec:
The TaskFilterSpec is passed as a parameter to CreateTaskCollector and allows you fetch specific tasks. e.g. If you wanted to fetch the tasks completed for a specific time range, by setting the time.begintime, time.endtime and time.timetype properties. Please refer the above documentation for more details.
Or, you could retrieve tasks by user name, by setting the username property in the TaskFilterSpec.
You can use a combination of different criterial for the taskfilterspec and then narrow down to a specific key, searching the taskHistoryCollector's taskinfo properties returned.
