code: @SafeVarargs
      public static <T> Set<T> of(T... elements) {
          Preconditions.checkNotNull(elements);
          return ImmutableSet.<T> builder().addAll(elements).build();
      }
docs: Creates a new immutable set that consists of given elements.
  
  @param elements the given elements
  @return a new immutable set that consists of given elements