Why Spring batch allows job without parameters to restart even if the job already completed successfullly?

[ELMORABITYounes]

Right now even if a job was completed successfuly, spring batch allow It to be restarted if It contains no identifying params as shown here:

if (!identifyingJobParameters.isEmpty()                                                        
		&& (status == BatchStatus.COMPLETED || status == BatchStatus.ABANDONED)) {            
	throw new JobInstanceAlreadyCompleteException(                                             
			"A job instance already exists and is complete for identifying parameters="       
					+ identifyingJobParameters + ".  If you want to run this job again, "    
					+ "change the parameters.");                                             
}                                                                                              

I am wondering why is that done like this? I mean if the job already completed why It does not throw JobInstanceAlreadyCompleteException? Shouldn't second job instance without param considered the same and hence not allow It to be restarted if already succeeded?