HashMap<String, String> result = new HashMap<>(getSystemProperties());
        if (project != null) {
            result.putAll(project.getModel().getProperties());
        }
        result.putAll(getUserProperties());
        return result;
    }

    @Nonnull
    @Override
    public Version getMavenVersion() {

    return super.put(key, value);
  }

  @Override
  public void putAll(Map<? extends Class<? extends @NonNull B>, ? extends B> map) {
    Map<Class<? extends @NonNull B>, B> copy = new LinkedHashMap<>(map);
    for (Entry<? extends Class<? extends @NonNull B>, B> entry : copy.entrySet()) {
      cast(entry.getKey(), entry.getValue());
    }
    super.putAll(copy);
  }

  @CanIgnoreReturnValue
  @Override
  @CheckForNull

    this(
        multimap.keySet().size(),
        (multimap instanceof ArrayListMultimap)
            ? ((ArrayListMultimap<?, ?>) multimap).expectedValuesPerKey
            : DEFAULT_VALUES_PER_KEY);
    putAll(multimap);
  }

  /**
   * Creates a new, empty {@code ArrayList} to hold the collection of values for an arbitrary key.
   */
  @Override
  List<V> createCollection() {

    this(
        multimap.keySet().size(),
        (multimap instanceof ArrayListMultimap)
            ? ((ArrayListMultimap<?, ?>) multimap).expectedValuesPerKey
            : DEFAULT_VALUES_PER_KEY);
    putAll(multimap);
  }

  /**
   * Creates a new, empty {@code ArrayList} to hold the collection of values for an arbitrary key.
   */
  @Override
  List<V> createCollection() {

                            // Note: using DOM instead of use of
                            // org.apache.maven.plugin.descriptor.PluginDescriptor
                            // as it would pull in dependency on:
                            // - maven-plugin-api (for model)
                            // - Plexus Container (for model supporting classes and exceptions)