code: public static <E> Set<E> newIdentityHashSet() {
      return Sets.newSetFromMap(Maps.<E, Boolean>newIdentityHashMap());
    }
docs: Creates an empty {@code Set} that uses identity to determine equality. It
  compares object references, instead of calling {@code equals}, to
  determine whether a provided object matches an element in the set. For
  example, {@code contains} returns {@code false} when passed an object that
  equals a set member, but isn't the same instance. This behavior is similar
  to the way {@code IdentityHashMap} handles key lookups.
  
  @since 8.0