@Override
	public String toString() {
		return getClass().getName();
	}
This method sorts the population in descending order while calculating
the selection probabilities. If the selection size is greater the
population size, the whole population is duplicated until the desired
sample size is reached.

@throws NullPointerException if the {@code population} or {@code opt} is
        {@code null}.
jenetics/src/main/java/io/jenetics/TruncationSelector.java