Associating workitem category to team area in RTC - rtc

Question

I could create WorkItem categories but getting an error while associating it to the teamarea.Getting error in the line createcategory.getAssociatedTeamAreas().add(newTAHandle). I am not getting how to return a boolean object of ITeamAreaHandle inside add method. Getting the compilation error : java.lang.UnsupportedOperationException
Please help. Below is the related code.
IWorkItemClient wservice = (IWorkItemClient) teamRepository.getClientLibrary(IWorkItemClient.class);
ICategory createcategory = wservice.createCategory(area, categoryName, null);
wservice.saveCategory(createcat, null);
if (!teamArea.equals("NULL")){
List teamAreas = area.getTeamAreas();
List <teamareahandle> teamlist = teamAreas;
ITeamAreaHandle newTAHandle = findTeamAreaByName(teamlist,teamAreaName,monitor);
createcategory.getAssociatedTeamAreas().add(newTAHandle);
}
//Method findTeamAreaByName
private static ITeamAreaHandle findTeamAreaByName (List<teamareahandle> teamlist, String teamAreaID, IProgressMonitor monitor) throws TeamRepositoryException {
for (ITeamAreaHandle teamAreaHandle : teamlist) {
ITeamArea teamArea = (ITeamArea)teamRepository.itemManager().fetchCompleteItem(teamAreaHandle,ItemManager.DEFAULT,monitor);
if (teamAreaID.equals(teamArea.getName())) {
return teamAreaHandle;
}
}
return null;
}

Answer 1

This thread comments:
The API to associate categories with team areas is internal.
If you need it anyway, cast the ICategory to the internal Category interface and use e.g. category.setDefaultTeamArea(...).
You can set the associated ones using:
((Category) category).getTeamAreas().add(teamArea);

Answer 2

Try this:
ICategory category = workItemClient.createCategory(projectArea, categoryName, getProgressMonitor());
((Category) category).doSetDefaultTeamArea(teamArea);
((Category) category).setArchived(false); //if it is archived
workItemClient.saveCategory(category, getProgressMonitor());