assertTrue(set.containsAll(Sets.newTreeSet(asList("a", "b", "f"))));
    assertFalse(set.containsAll(Sets.newTreeSet(asList("d"))));
    assertFalse(set.containsAll(Sets.newTreeSet(asList("z"))));
    assertFalse(set.containsAll(Sets.newTreeSet(asList("b", "d"))));
    assertFalse(set.containsAll(Sets.newTreeSet(asList("f", "d", "a"))));
  }

                  @Override
                  protected Set<String> create(String[] elements) {
                    Set<String> set1 = newHashSet(elements);
                    set1.add(samples().e3());
                    Set<String> set2 = newHashSet(elements);
                    set2.add(samples().e4());
                    return Sets.intersection(set1, set2);
                  }
                })

      if (set.isEmpty()) {
        /*
         * The (tooLow + 1, tooHigh) arguments below would be invalid because tooLow would be
         * greater than tooHigh.
         */
        return ContiguousSet.create(Range.openClosed(0, 1), DiscreteDomain.integers()).subSet(0, 1);
      }
      int tooHigh = set.last() + 1;
      int tooLow = set.first() - 1;
      set.add(tooHigh);

     *
     * @return The source of the POM or {@code null} if not set.
     */
    ModelSource getModelSource();

    /**
     * Sets the source of the POM to process. Eventually, either {@link #setModelSource(ModelSource)} or
     * {@link #setPomPath(Path)} must be set.
     *
     * @param modelSource The source of the POM to process, may be {@code null}.
     * @return This request, never {@code null}.
     */

    /**
     * Gets the global settings file.
     *
     * @return The global settings file or {@code null} if none.
     */
    File getGlobalSettingsFile();

    /**
     * Sets the global settings file. A non-existent settings file is equivalent to empty settings. If both user
     * settings and global settings are given, the user settings take precedence.
     *

    private File projectDirectory;

    @Override
    public List<String> getActiveProfileIds() {
        return activeProfileIds;
    }

    /**
     * Sets the identifiers of those profiles that should be activated by explicit demand.
     *
     * @param activeProfileIds The identifiers of those profiles to activate, may be {@code null}.
     * @return This context, never {@code null}.

    elements.add(null);
    Set<E> other = MinimalSet.from(elements);

    assertFalse(
        "Two Sets should not be equal if exactly one of them contains null.",
        getSet().equals(other));
  }

  @CollectionSize.Require(absent = CollectionSize.ZERO)
  public void testEquals_smallerSet() {
    Collection<E> fewerElements = getSampleElements(getNumElements() - 1);
    assertFalse(

    elements.add(null);
    Set<E> other = MinimalSet.from(elements);

    assertFalse(
        "Two Sets should not be equal if exactly one of them contains null.",
        getSet().equals(other));
  }

  @CollectionSize.Require(absent = CollectionSize.ZERO)
  public void testEquals_smallerSet() {
    Collection<E> fewerElements = getSampleElements(getNumElements() - 1);
    assertFalse(

      if (set.isEmpty()) {
        /*
         * The (tooLow + 1, tooHigh) arguments below would be invalid because tooLow would be
         * greater than tooHigh.
         */
        return ContiguousSet.create(Range.openClosed(0, 1), DiscreteDomain.integers()).subSet(0, 1);
      }
      int tooHigh = set.last() + 1;
      int tooLow = set.first() - 1;
      set.add(tooHigh);

    /**
     * Gets the artifact to resolve metadata for.
     *
     * @return The artifact to resolve metadata for or {@code null} if not set.
     */
    Artifact getArtifact();

    /**
     * Sets the artifact for which to resolve metadata.
     *
     * @param artifact The artifact for which to resolve metadata.
     * @return This request, never {@code null}.
     */