return this;
    }

    private Plugin findPlugin(Model model, String groupId, String artifactId) {
        if (Objects.requireNonNull(groupId, "groupId cannot be null").isEmpty()) {
            throw new IllegalArgumentException("groupId cannot be empty");
        }
        if (Objects.requireNonNull(artifactId, "artifactId cannot be null").isEmpty()) {
            throw new IllegalArgumentException("artifactId cannot be empty");

    return requireNonNull(outEdgeMap.get(edge));
  }

  @Override
  public N removeInEdge(E edge, boolean isSelfLoop) {
    if (isSelfLoop) {
      checkNonNegative(--selfLoopCount);
    }
    N previousNode = inEdgeMap.remove(edge);
    // We're relying on callers to call this method only with an edge that's in the graph.
    return requireNonNull(previousNode);
  }

  @Override

import org.eclipse.aether.artifact.ArtifactTypeRegistry;

import static java.util.Objects.requireNonNull;

class TypeRegistryAdapter implements ArtifactTypeRegistry {
    private final TypeRegistry typeRegistry;

    TypeRegistryAdapter(TypeRegistry typeRegistry) {
        this.typeRegistry = requireNonNull(typeRegistry, "typeRegistry");
    }

    @Override
    public ArtifactType get(String typeId) {

        // TODO(b/139735208): Figure out what to do when the factory returns null.
        requireNonNull(thread);
        if (nameFormat != null) {
          // requireNonNull is safe because we create `count` if (and only if) we have a nameFormat.
          thread.setName(format(nameFormat, requireNonNull(count).getAndIncrement()));
        }
        if (daemon != null) {
          thread.setDaemon(daemon);

    @Override
    public Model read(File input, Map<String, ?> options) throws IOException {
        Objects.requireNonNull(input, "input cannot be null");
        return read(input.toPath(), options);
    }

    @Override
    public Model read(Path path, Map<String, ?> options) throws IOException {
        Objects.requireNonNull(path, "path cannot be null");

        try (InputStream in = Files.newInputStream(path)) {

    if (nodeU == null) {
      return false;
    }

    // requireNonNull is safe because of the edgeToReferenceNode check above.
    NetworkConnections<N, E> connectionsU = requireNonNull(nodeConnections.get(nodeU));
    N nodeV = connectionsU.adjacentNode(edge);
    NetworkConnections<N, E> connectionsV = requireNonNull(nodeConnections.get(nodeV));
    connectionsU.removeOutEdge(edge);

      canRemove = true;
      /*
       * requireNonNull is safe because occurrencesLeft starts at 0, forcing us to initialize
       * currentEntry above. After that, we never clear it.
       */
      return requireNonNull(currentEntry).getKey();
    }

    @Override
    public void remove() {
      checkRemove(canRemove);
      /*
       * requireNonNull is safe because canRemove is set to true only after we initialize

    protected CommonsCliOptions(String source, CLIManager cliManager, CommandLine commandLine) {
        this.source = requireNonNull(source);
        this.cliManager = requireNonNull(cliManager);
        this.commandLine = requireNonNull(commandLine);
    }

    @Override
    public String source() {
        return source;
    }

    @Override
    public Optional<Map<String, String>> userProperties() {

      switch (balanceFactor()) {
        case -2:
          // requireNonNull is safe because right must exist in order to get a negative factor.
          requireNonNull(right);
          if (right.balanceFactor() > 0) {
            right = right.rotateRight();
          }
          return rotateLeft();
        case 2:
          // requireNonNull is safe because left must exist in order to get a positive factor.

            VersionScheme versionScheme) {
        this.metadataResolver = Objects.requireNonNull(metadataResolver, "metadataResolver cannot be null");
        this.syncContextFactory = Objects.requireNonNull(syncContextFactory, "syncContextFactory cannot be null");
        this.repositoryEventDispatcher =
                Objects.requireNonNull(repositoryEventDispatcher, "repositoryEventDispatcher cannot be null");