Entry<?, ?> entry = parts.next();
        appendable.append(joiner.toString(entry.getKey()));
        appendable.append(keyValueSeparator);
        appendable.append(joiner.toString(entry.getValue()));
        while (parts.hasNext()) {
          appendable.append(joiner.separator);
          Entry<?, ?> e = parts.next();
          appendable.append(joiner.toString(e.getKey()));
          appendable.append(keyValueSeparator);

      Entry<K, Collection<V>> entry = sortedMap().ceilingEntry(key);
      return (entry == null) ? null : wrapEntry(entry);
    }

    @Override
    public @Nullable K ceilingKey(@ParametricNullness K key) {
      return sortedMap().ceilingKey(key);
    }

    @Override
    public @Nullable Entry<K, Collection<V>> higherEntry(@ParametricNullness K key) {

      }
      return false;
    }

    @Override
    public boolean remove(@Nullable Object o) {
      if (o instanceof Map.Entry) {
        Map.Entry<?, ?> entry = (Map.Entry<?, ?>) o;
        return multimap().remove(entry.getKey(), entry.getValue());
      }
      return false;
    }

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

            // feature
            for (final Map.Entry<String, String> entry : featureMap.entrySet()) {
                parser.setFeature(entry.getKey(), "true".equalsIgnoreCase(entry.getValue()));
            }

            // property
            for (final Map.Entry<String, String> entry : propertyMap.entrySet()) {
                parser.setProperty(entry.getKey(), entry.getValue());
            }

      if (object instanceof Entry) {
        Entry<?, ?> entry = (Entry<?, ?>) object;
        return multimap.containsEntry(entry.getKey(), entry.getValue());
      }
      return false;
    }

    // redeclare to help optimizers with b/310253115
    @SuppressWarnings("RedundantOverride")
    @Override
    @J2ktIncompatible
    @GwtIncompatible
        Object writeReplace() {

            for (final Map.Entry<String, Object> entry : attributeMap.entrySet()) {
                factory.setAttribute(entry.getKey(), entry.getValue());
            }

            for (final Map.Entry<String, String> entry : featureMap.entrySet()) {
                factory.setFeature(entry.getKey(), "true".equalsIgnoreCase(entry.getValue()));
            }

    @SuppressWarnings("unchecked")
    Entry<String, String>[] array = (Entry<String, String>[]) new Entry<?, ?>[entries.length];
    int i = 0;
    for (Object o : entries) {
      @SuppressWarnings("unchecked")
      Entry<String, String> e = (Entry<String, String>) o;
      array[i++] = e;
    }
    return create(array);
  }

  protected abstract Map<String, String> create(Entry<String, String>[] entries);

  @Override

    @Override
    protected BiMap<String, String> create(Entry<String, String>[] entries) {
      ImmutableBiMap.Builder<String, String> builder = ImmutableBiMap.builder();
      for (Entry<String, String> entry : entries) {
        checkNotNull(entry);
        builder.put(entry.getKey(), entry.getValue());
      }
      return builder.build();
    }
  }

  private Entry<K, V> nullKeyEntry;
  private Entry<K, V> nullValueEntry;
  private Entry<K, V> nullKeyValueEntry;
  private Entry<K, V> presentKeyNullValueEntry;

  @Override
  public void setUp() throws Exception {
    super.setUp();
    nullKeyEntry = entry(null, v3());
    nullValueEntry = entry(k3(), null);
    nullKeyValueEntry = entry(null, null);

  @Override
  protected void assertMoreInvariants(Map<K, V> map) {
    // TODO: can these be moved to MapInterfaceTest?
    for (Entry<K, V> entry : map.entrySet()) {
      assertEquals(entry.getKey() + "=" + entry.getValue(), entry.toString());
    }

    assertEquals("{" + JOINER.join(map.entrySet()) + "}", map.toString());