code: public static <T> Set<T> intersection(Set<T> setA, Set<T> setB) {
          Set<T> intersection = new HashSet<T>(setA);
          intersection.retainAll(setB);
          return intersection;
      }
docs: This method finds the intersection between set A and set B
  @param setA set A
  @param setB set B
  @param <T> type
  @return a new set containing the intersection