Setting start-workers to false makes sure workerFactory.start() is not called and you would have to autowire WorkerFactory and call start on it explicitly.
What should be considered as custom changes
Currently could be to create additional workers that have not been configured or auto-discovered via factory.newWorker(...) or get existing worker from factory and register additional workflow/activity types, via factory.tryGetWorker(tqname).
is there a sample Temporal SpringBoot autoconfigure project available to refer to