code: public void terminateWorkflow(String workflowId, String reason) {
          Preconditions.checkArgument(StringUtils.isNotBlank(workflowId), "workflow id cannot be blank");
          delete(new Object[]{"reason", reason}, "workflow/{workflowId}", workflowId);
      }
docs: Terminates the execution of the given workflow instance
  
  @param workflowId the id of the workflow to be terminated
  @param reason     the reason to be logged and displayed