*/
public class NotSpec<T> implements Spec<T> {
    private Spec<? super T> sourceSpec;

    public NotSpec(Spec<? super T> sourceSpec) {
        this.sourceSpec = sourceSpec;
    }

    Spec<? super T> getSourceSpec() {
        return sourceSpec;
    }

    @Override
    public boolean isSatisfiedBy(T element) {
        return !sourceSpec.isSatisfiedBy(element);
    }

            return satisfyAll();
        }
        if (spec instanceof NotSpec) {
            NotSpec<? super T> notSpec = Cast.uncheckedNonnullCast(spec);
            return Cast.uncheckedNonnullCast(notSpec.getSourceSpec());
        }
        return new NotSpec<>(spec);
    }