code: protected void setRandom(double lower, double upper, Random generator) {
          double range = upper - lower;
  
          x = generator.nextDouble() * range + lower;
          y = generator.nextDouble() * range + lower;
          z = generator.nextDouble() * range + lower;
      }
docs: Sets the elements of this vector to uniformly distributed random values
  in a specified range, using a supplied random number generator.
  
  @param lower
  lower random value (inclusive)
  @param upper
  upper random value (exclusive)
  @param generator
  random number generator