private static final Predicate<@Nullable Integer> EVEN = input -> input == null || input % 2 == 0;
  static final Predicate<Entry<String, Integer>> CORRECT_LENGTH =
      input -> input.getKey().length() == input.getValue();

  abstract Map<String, Integer> createUnfiltered();

  public void testFilteredKeysIllegalPut() {
    Map<String, Integer> unfiltered = createUnfiltered();

    }
  }

  @Override
  final Iterator<E> elementIterator() {
    return new Itr<E>() {
      @Override
      @ParametricNullness
      E result(int entryIndex) {
        return backingMap.getKey(entryIndex);
      }
    };
  }

  @Override
  final Iterator<Entry<E>> entryIterator() {
    return new Itr<Entry<E>>() {
      @Override
      Entry<E> result(int entryIndex) {

    super(delegate);

    ImmutableMap.Builder<V, K> builder = ImmutableMap.builder();
    for (Entry<K, V> entry : delegate.entrySet()) {
      builder.put(entry.getValue(), entry.getKey());
    }
    ImmutableMap<V, K> backwardMap = builder.build();
    this.inverse = new RegularImmutableBiMap<V, K>(backwardMap, this);
  }

        return entryIterator.hasNext();
      }

      @Override
      public K next() {
        return entryIterator.next().getKey();
      }
    };
  }

  Spliterator<K> keySpliterator() {
    return CollectSpliterators.map(entrySet().spliterator(), Entry::getKey);
  }

  @LazyInit @RetainedWith @CheckForNull private transient ImmutableCollection<V> values;

  /**

        for (Map.Entry<MavenDependencyKey, PomDependencyData> entry : pomParent.getDependencies().entrySet()) {
            if (!dependencies.containsKey(entry.getKey())) {
                dependencies.put(entry.getKey(), entry.getValue());
            }
        }

        for (PomProfile pomProfile : parseActivePomProfiles()) {
            for (PomDependencyData dependency : pomProfile.getDependencies()) {

          RangeMap<Integer, Integer> expected = TreeRangeMap.create();
          for (Entry<Range<Integer>, Integer> entry : rangeMap.asMapOfRanges().entrySet()) {
            if (entry.getKey().isConnected(subRange)) {
              expected.put(entry.getKey().intersection(subRange), entry.getValue());
            }
          }
          RangeMap<Integer, Integer> subRangeMap = rangeMap.subRangeMap(subRange);

      }
      checkArgument(!containsValue(value), "value already present: %s", value);
      V oldValue = delegate.setValue(value);
      checkState(Objects.equal(value, get(getKey())), "entry no longer in map");
      updateInverseMap(getKey(), true, oldValue, value);
      return oldValue;
    }
  }

  Iterator<Entry<K, V>> entrySetIterator() {
    final Iterator<Entry<K, V>> iterator = delegate.entrySet().iterator();

    public void define(@Nullable Map<String, Object> args) {
        if (args == null) {
            return;
        }
        for (Map.Entry<String, Object> arg: args.entrySet()) {
            setProperty(arg.getKey(), arg.getValue());
        }
    }

    private void setProperty(String property, Object value) {

        }

        private String cachePath(String group, String module, String version) {
            return Pattern.quote("${userHomeDir.path.replace(File.separator, '/')}") + "/caches/${CacheLayout.MODULES.getKey()}/${CacheLayout.FILE_STORE.getKey()}/" + Pattern.quote("${group}/${module}/${version}/") + "\\w+/"
        }

        void assertHasNoSource() {
            assert !entry.@sourcepath
        }

        final PrimaryCipher cipher = ComponentUtil.getPrimaryCipher();
        ParameterUtil.parse(value).entrySet().stream().map(e -> {
            final String k = e.getKey();
            final String v = e.getValue();
            if (properyPattern.matcher(k).matches() && !v.startsWith(CIPHER_PREFIX)) {
                return new Pair<>(k, CIPHER_PREFIX + cipher.encrypt(v));
            }