Set<String> friends = Sets.newHashSet("Tom", "Joe", "Dave");
    Set<String> enemies = Sets.newHashSet("Dick", "Harry", "Tom");

    Set<String> goodFriends = Sets.difference(friends, enemies);
    assertEquals(2, goodFriends.size());

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

  public static <E> Interner<E> newWeakInterner() {
    return newBuilder().weak().build();
  }

  @VisibleForTesting
  static final class InternerImpl<E> implements Interner<E> {
    // MapMaker is our friend, we know about this type
    @VisibleForTesting final MapMakerInternalMap<E, Dummy, ?, ?> map;

    private InternerImpl(MapMaker mapMaker) {
      this.map =

      } catch (ClassNotFoundException runningUnderAndroidOrJava8) {
        /*
         * I'm not sure that we could actually get here for *Android*: I would expect us to enter
         * the POSIX code path instead. And if we tried this code path, we'd have trouble unless we
         * were running under a new enough version of Android to support NIO.
         *

    resetContainer();
  }

  /**
   * @return the contents of the container under test, for use by {@link #expectContents(Object[])
   *     expectContents(E...)} and its friends.
   */
  protected abstract Collection<E> actualContents();

  /**
   * Replaces the existing container under test with a new container created by the subject
   * generator.
   *

   * <ul>
   *   <li>The visible constructor or visible static factory method with the most parameters is used
   *       to construct the sample instances. In case of tie, the candidate constructors or
   *       factories are tried one after another until one can be used to construct sample
   *       instances.
   *   <li>For the constructor or static factory method used to construct instances, it's checked

    URLClassLoader sepLoader = new URLClassLoader(getClassPathUrls(), myLoader.getParent());
    // sepLoader is the loader that we will use to load the parallel FinalizableReferenceQueue (FRQ)
    // and friends, and that we will eventually expect to see garbage-collected. The assumption
    // is that the ClassLoader of this test is a URLClassLoader, and that it loads FRQ itself

   * the capacity, it is doubled in size unless some other thread
   * holds the lock. If a hashed slot is empty, and lock is
   * available, a new Cell is created. Otherwise, if the slot
   * exists, a CAS is tried.  Retries proceed by "double hashing",
   * using a secondary hash (Marsaglia XorShift) to try to find a
   * free slot.
   *
   * The table size is capped because, when there are more threads

       *   cause if this Future has failed.
       *
       * - And this future *has* failed: This method is called only from handleException (through
       *   getOrInitSeenExceptions). handleException tried to call setException and failed, so
       *   either this Future was cancelled (which we ruled out with the isCancelled check above),
       *   or it had already failed. (It couldn't have completed *successfully* or even had

   *   <li>The non-private constructor or non-private static factory method with the most parameters
   *       is used to construct the sample instances. In case of tie, the candidate constructors or
   *       factories are tried one after another until one can be used to construct sample
   *       instances.
   *   <li>For the constructor or static factory method used to construct instances, it's checked

   *   <li>The non-private constructor or non-private static factory method with the most parameters
   *       is used to construct the sample instances. In case of tie, the candidate constructors or
   *       factories are tried one after another until one can be used to construct sample
   *       instances.
   *   <li>For the constructor or static factory method used to construct instances, it's checked