Set<String> optionalSelectors = projectActivation.getOptionalActiveProjectSelectors();
        if (!requiredSelectors.isEmpty() || !optionalSelectors.isEmpty()) {
            Set<MavenProject> selectedProjects = new HashSet<>(requiredSelectors.size() + optionalSelectors.size());
            selectedProjects.addAll(

                    + (pathAdjustment.isEmpty() ? 1 : 2));

            url.append(parentUrl);
            concatPath(url, pathAdjustment);
            concatPath(url, childPath);

            return url.toString();
        }

        private void concatPath(StringBuilder url, String path) {
            if (!path.isEmpty()) {

                if (dependency.getGroupId() == null
                        || dependency.getGroupId().isEmpty()
                        || dependency.getArtifactId() == null
                        || dependency.getArtifactId().isEmpty()
                        || dependency.getVersion() == null
                        || dependency.getVersion().isEmpty()) {
                    // guard against case where best-effort resolution for invalid models is requested

    @Nonnull
    default Optional<Version> getLowerVersion() {
        return getVersions().isEmpty()
                ? Optional.empty()
                : Optional.of(getVersions().get(0));
    }

    @Nonnull
    default Optional<Version> getHigherVersion() {
        return getVersions().isEmpty()
                ? Optional.empty()
                : Optional.of(getVersions().get(getVersions().size() - 1));
    }

        }
        String str1 = request.getClassifier();
        String classifier =
                str1 != null && !str1.isEmpty() ? request.getClassifier() : type != null ? type.getClassifier() : null;
        String str = request.getExtension();
        String extension =
                str != null && !str.isEmpty() ? request.getExtension() : type != null ? type.getExtension() : null;
        return new DefaultArtifact(
                session,

            String str1 = request.getClassifier();
            String classifier = str1 != null && !str1.isEmpty()
                    ? request.getClassifier()
                    : type != null ? type.getClassifier() : "";
            String str = request.getExtension();
            String extension =
                    str != null && !str.isEmpty() ? request.getExtension() : type != null ? type.getExtension() : "";

        ArtifactRepository repo = null;

        if (versions.releaseVersion != null && !versions.releaseVersion.isEmpty()) {
            version = versions.releaseVersion;
            repo = versions.releaseRepository;
        } else if (versions.latestVersion != null && !versions.latestVersion.isEmpty()) {
            version = versions.latestVersion;
            repo = versions.latestRepository;
        }

            projectKeys.add(key);
        }
        return projectKeys;
    }

    public boolean isEmpty() {
        return items.isEmpty();
    }

    /**
     * @return a set of all the projects managed by the build
     */
    public Set<MavenProject> getProjects() {

    }

    public Set<Artifact> getRequestedArtifacts() {
        return requestedArtifacts;
    }

    public boolean hasMissingArtifacts() {
        return missingArtifacts != null && !missingArtifacts.isEmpty();
    }

    public List<Artifact> getMissingArtifacts() {
        return missingArtifacts == null ? Collections.emptyList() : Collections.unmodifiableList(missingArtifacts);
    }

                PluginContainer source,
                boolean sourceDominant,
                Map<Object, Object> context) {
            List<Plugin> src = source.getPlugins();
            if (!src.isEmpty()) {
                List<Plugin> tgt = target.getPlugins();

                Map<Object, Plugin> merged = new LinkedHashMap<>((src.size() + tgt.size()) * 2);

                for (Plugin element : tgt) {