@Override
	public boolean addAll(final Collection<? extends T> elements) {
		final int sum = elements.stream()
			.mapToInt(e -> add(e) ? 1 : 0)
			.sum();
		return sum > 0;
	}
Adds all elements of the given collection to {@code this} pareto front.

@implNote
The runtime complexity of this operation is
{@code O(elements.size()*this.size())}.

@param elements the elements to add to {@code this} pareto front
@return {@code true} if {@code this} pareto front has been changed,
        {@code false} otherwise
jenetics.ext/src/main/java/io/jenetics/ext/moea/ParetoFront.java