WeibullGen Parameters using umontreal.iro.lecuyer.randvar package java

I am trying to generate weibull random numbers using WeibullGen from umontreal.iro.lecuyer.randvar package this is my code

RandomStream stream = new MRG32k3a();
for(int i=0;i<5;i++) {
   int result = WeibullGen.nextDouble(stream, alp, lam,bet);
   System.out.println(result);
}

But I am a little confused about the parameters I mean does lam means the scale or the rate parameters, I think alp means the shape parameter. finally, I am confused about the last parameter bet what it present. I tried to look online but it wasn't clear to me. Thanks in advance