We need to create validators for each status. The validator will check if transition from current state is allowed or not. All validators are injected into WorkflowExecutionValidator. private List<Validator> validators WorkflowExecutionValidator will pick up an appropriate validator from a list and check if transition is allowed. Validators are implemented for each workflow execution status Validators are applied in production code

workflowExecution.setStatus(WorkflowExecutionStatus.COMPLETED);
        workflowExecutionValidator.validateTransition(
                workflowExecution,
                WorkflowExecutionStatus.COMPLETED, DummyUser.ADMIN);