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How to get the corresponding stream of a known workspace?
One answer

First, you have to retrieve the IWorkspace object for the build workspace from the UUID param:
UUID uuid = ...
IWorkspaceHandle wksH = IWorkspace.ITEM_TYPE.createItemHandle(uuid, null);
IRepositoryItemService itemService = getService(IRepositoryItemService.class);
IWorkspace wks = itemService.fetchItem(wksH, IRepositoryItemService.COMPLETE);
Then, you can retrieve the flows from that workspace:
List<FlowEntry> flows = ((Workspace) wks).getFlows();
Notice you have to cast the IWorkspace object to a Workspace object to invoke the getFlows() method.
Finally, you will have to filter that list to get only the deliver targets:
if ((flow.getFlags() & FlowFlags.DELIVER) != 0) {
// ...
}
Cheers.