this.source = source;
            this.attributesFactory = attributesFactory;
        }

        @Override
        public ImmutableSet<Attribute<?>> keySet() {
            return getDesugared().keySet();
        }

        @Deprecated
        @Override
        public <T> AttributeContainer attribute(Attribute<T> key, T value) {
            return getDesugared().attribute(key, value);

  }

  @Override
  SortedMap<K, Collection<V>> backingMap() {
    return (SortedMap<K, Collection<V>>) super.backingMap();
  }

  @Override
  public SortedSet<K> keySet() {
    return (SortedSet<K>) super.keySet();
  }

  @Override
  Set<K> createKeySet() {
    return createMaybeNavigableKeySet();
  }

    for (K key : multimap().keySet()) {
      SortedSet<V> valueSet = (SortedSet<V>) multimap().asMap().get(key);
      assertEquals(multimap().valueComparator(), valueSet.comparator());
    }
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testAsMapRemoveImplementsSortedSet() {
    List<K> keys = new ArrayList<>(multimap().keySet());
    for (K key : keys) {
      resetCollection();

        entryIterator(), size(), (this instanceof SetMultimap) ? Spliterator.DISTINCT : 0);
  }

  @LazyInit @CheckForNull private transient Set<K> keySet;

  @Override
  public Set<K> keySet() {
    Set<K> result = keySet;
    return (result == null) ? keySet = createKeySet() : result;
  }

  abstract Set<K> createKeySet();

  @LazyInit @CheckForNull private transient Multiset<K> keys;

  @Override

    return new RowSortedMap();
  }

  @WeakOuter
  private class RowSortedMap extends RowMap implements SortedMap<R, Map<C, V>> {
    @Override
    public SortedSet<R> keySet() {
      return (SortedSet<R>) super.keySet();
    }

    @Override
    SortedSet<R> createKeySet() {
      return new Maps.SortedKeySet<>(this);
    }

    @Override
    @CheckForNull

        return systemProjectProperties;
    }

    private Map<String, String> projectPropertiesFromEnvironmentVariables() {
        Map<String, String> envProjectProperties = byPrefix(ENV_PROJECT_PROPERTIES_PREFIX, environment.getVariables());
        LOGGER.debug("Found env project properties: {}", envProjectProperties.keySet());
        return envProjectProperties;
    }

        return delegate.asImmutable();
    }

    @Override
    public Map<Attribute<?>, ?> asMap() {
        return delegate.asMap();
    }

    @Override
    public Set<Attribute<?>> keySet() {
        return delegate.keySet();
    }

    @Override
    public <T> AttributeContainer attribute(Attribute<T> key, T value) {
        assertMutable();
        delegate.attribute(key, value);
        return this;
    }

        parent.putAll(m);
    }

    @Override
    public void clear() {
        parent.clear();
    }

    @Override
    public Set<String> keySet() {
        return parent.keySet();
    }

    @Override
    public Collection<Object> values() {
        return parent.values();
    }

    @Override
    public Set<java.util.Map.Entry<String, Object>> entrySet() {

    assertTrue(multimap().containsKey(k0()));
  }

  public void testContainsKeyNo() {
    assertFalse(multimap().containsKey(k3()));
  }

  public void testContainsKeysFromKeySet() {
    for (K k : multimap().keySet()) {
      assertTrue(multimap().containsKey(k));
    }
  }

  public void testContainsKeyAgreesWithGet() {
    for (K k : sampleKeys()) {
      assertEquals(!multimap().get(k).isEmpty(), multimap().containsKey(k));

        // need to take copy to prevent ConcurrentModificationException
        List<String> keysToRemove = Lists.newArrayList(Sets.difference(System.getenv().keySet(), source.keySet()));
        for (String key : keysToRemove) {
            removeEnvironmentVariable(key);
        }
        for (Map.Entry<String, String> entry : source.entrySet()) {