The requirement that an OSH call completeStep/stepCompleted in its execute method dates from when we supported recursive step execution. It could have been eliminated when we dropped support for recursive step execution, but that didn't occur to me until yesterday.

All stepCompleted() does is register a default ResultHandler. AbstractOperationContext.executeStep could do the same thing after calling step.execute(...) if that call returns normally and it sees that no ResultHandler was registered with the step.

Even I fairly often make the mistake of forgetting to add a stepCompleted call.