* @param numberOfResults - maximal number of top results to keep.
*/
@SuppressWarnings({ "unchecked", "rawtypes" })
public TopResultsMapBackedSet(final int numberOfResults) {
super(new DefaultKeyExtractor());
this.sortedResults = new TreeSet<R>(new RecommendationResultComparator());
this.numberOfResults = numberOfResults;
this.comp = new RecommendationResultComparator();
}