code: private double calculateRespTimeModule(double visits, double lambda, double mu) {
  
        double utilization = lambda / mu;
        if (utilization > 1.0) {
           return Double.POSITIVE_INFINITY;
        }
        double respTimeVisit = (1.0 / mu) / (1.0 - utilization);
  
        return visits * respTimeVisit;
  
     }
docs: /*
  Here they are used the Queueing Network theory basics.