code: private void doMutation(double probability, DoubleSolution solution) {
      for (int i = 0; i < solution.getNumberOfVariables(); i++) {
        if (randomGenerator.getRandomValue() <= probability) {
        	Double value = solution.getLowerBound(i) +
        			((solution.getUpperBound(i) - solution.getLowerBound(i)) * randomGenerator.getRandomValue()) ;
        	
        	solution.setVariableValue(i, value) ;
        }
      }
  	}
docs: Implements the mutation operation