assertEquals(5, all.size());

    ImmutableSet<String> immut = Sets.union(friends, enemies).immutableCopy();
    HashSet<String> mut = Sets.union(friends, enemies).copyInto(new HashSet<String>());

    enemies.add("Buck");
    assertEquals(6, all.size());
    assertEquals(5, immut.size());
    assertEquals(5, mut.size());
  }

  public void testIntersection() {
    Set<String> friends = Sets.newHashSet("Tom", "Joe", "Dave");

    assertEquals(5, all.size());

    ImmutableSet<String> immut = Sets.union(friends, enemies).immutableCopy();
    HashSet<String> mut = Sets.union(friends, enemies).copyInto(new HashSet<String>());

    enemies.add("Buck");
    assertEquals(6, all.size());
    assertEquals(5, immut.size());
    assertEquals(5, mut.size());
  }

  public void testIntersection() {
    Set<String> friends = Sets.newHashSet("Tom", "Joe", "Dave");

	// - 0::/../crio-45490e76e0878aaa4d9808f7d2eefba37f093c3efbba9838b6d8ab804d9bd814.scope
	// First trim off any .scope suffix. This allows for a cleaner regex since
	// we don't have to muck with greediness. TrimSuffix is no-copy so this
	// is cheap.
	cgroupPath = strings.TrimSuffix(cgroupPath, ".scope")

	var matchResults map[string]string
	for _, regex := range cgroupREs {