Is WorkflowTransitionService bugged?

Using the Project Blueprint API, I was trying to add various conditions/post-functions to the workflows after the system creates the workflows.

I am able to modify the workflow by creating a draft, adding various ConditionDescriptors/FunctionDescriptors to the ActionDescriptor.unconditionalResult, but I don’t seem to be able to use the WorkflowTransitionService class to do this.

When I use the addConditionToWorkflow(), addPostFunctionToWorkflow(), or addScreenToWorkflow() methods, I receive an EMPTY ErrorCollection, which to me implies that the operation was successful. However, after saving the workflow and the hook completes, nothing was added to the workflow.

I’d prefer to use the WorkflowTransitionService as it prevents me from needing to write code directly against OS classes. Is this class no longer working? From my point of view, it doesn’t work at all.