@Override
    public MavenExecutionRequest addProxy(Proxy proxy) {
        Objects.requireNonNull(proxy, "proxy cannot be null");

        for (Proxy p : getProxies()) {
            if (p.getId() != null && p.getId().equals(proxy.getId())) {
                return this;
            }
        }

        getProxies().add(proxy);

        return this;
    }

    @Override

            }
            item = newItem;
        }

        public StemmerOverrideItem write(final StemmerOverrideItem oldItem) {
            try {
                if ((item == null) || (item.getId() != oldItem.getId()) || !item.isUpdated()) {
                    writer.write(oldItem.toLineString());
                    writer.write(Constants.LINE_SEPARATOR);
                    return oldItem;
                }

    public ArtifactRepositoryPolicy getReleases() {
        return releases;
    }

    public String getKey() {
        return getId();
    }

    public String toString() {
        StringBuilder sb = new StringBuilder(256);

        sb.append("      id: ").append(getId()).append(LS);
        sb.append("      url: ").append(getUrl()).append(LS);
        sb.append("   layout: ").append(layout != null ? layout : "none");

        List<MavenProject> sorted = this.sorter.getSortedProjects();
        for (int index = 0; index < sorted.size(); index++) {
            MavenProject project = sorted.get(index);
            String id = ProjectSorter.getId(project);
            this.projects.put(id, project);
            this.order.put(project, index);
        }
    }

    /**
     * @since 3.5.0
     */
    public List<MavenProject> getAllProjects() {

            return null;
        }

        public String getProtocol() {
            return repository.getProtocol();
        }

        public String getId() {
            return repository.getId();
        }

        public void setId(String id) {}

        public ArtifactRepositoryPolicy getSnapshots() {
            return null;
        }

                && a1.isOptional() == a2.isOptional();
    }

    private static int repositoryHashCode(ArtifactRepository repository) {
        int result = 17;
        result = 31 * result + (repository.getId() != null ? repository.getId().hashCode() : 0);
        return result;
    }

    private static int repositoriesHashCode(List<ArtifactRepository> repositories) {
        int result = 17;

                    try {
                        wagonManager.getArtifactMetadata(metadata, repository, file, policy.getChecksumPolicy());
                    } catch (ResourceDoesNotExistException e) {
                        getLogger().debug(metadata + " could not be found on repository: " + repository.getId());

        StringBuilder repos = new StringBuilder("[");

        if (localRepository != null) {
            repos.append(localRepository.getId())
                    .append(" (")
                    .append(localRepository.getBasedir())
                    .append(")");
        }

        if (remoteRepositories != null && !remoteRepositories.isEmpty()) {

                    "Skipping disabled repository " + repository.getId() + " for resolution of " + artifact.getId());

        } else if (artifact.isSnapshot() || !artifact.getFile().exists()) {
            if (force || updateCheckManager.isUpdateRequired(artifact, repository)) {
                logger.debug("Trying repository " + repository.getId() + " for resolution of " + artifact.getId()
                        + " from " + remotePath);

        }
        return result;
    }

    public static String getLayout(ArtifactRepository repo) {
        try {
            return repo.getLayout().getId();
        } catch (LinkageError e) {
            /*
             * NOTE: getId() was added in 3.x and is as such not implemented by plugins compiled against 2.x APIs.
             */
            String className = repo.getLayout().getClass().getSimpleName();