@Override
  public int occurrences(Object element) {
    return contains(element) ? 1 : 0;
  }
Implementation of SelectResults that extends TreeSet This is the sorted version of ResultSet used
for order by clause If the elements are Structs, then use SortedStructSet instead.

@since GemFire 4.0
geode-core/src/main/java/org/apache/geode/cache/query/internal/SortedResultSet.java