if (empty(groupId)) {
            throw new InvalidArtifactRTException(
                    groupId, artifactId, getVersion(), type, "The groupId cannot be empty.");
        }

        if (artifactId == null) {
            throw new InvalidArtifactRTException(
                    groupId, artifactId, getVersion(), type, "The artifactId cannot be empty.");
        }

        if (type == null) {

        return Objects.equals(a1.getGroupId(), a2.getGroupId())
                && Objects.equals(a1.getArtifactId(), a2.getArtifactId())
                && Objects.equals(a1.getVersion(), a2.getVersion());
    }

    private Map<String, String> toProperties(Map<String, String> dominant, Map<String, String> recessive) {
        Map<String, String> props = new HashMap<>();
        if (recessive != null) {

        } catch (InvalidVersionSpecificationException e) {
            result.addException(e);
            throw new VersionRangeResolutionException(result);
        }

        result.setVersionConstraint(versionConstraint);

        if (versionConstraint.getRange() == null) {
            result.addVersion(versionConstraint.getVersion());
        } else {

        final Map<String, String> item = new HashMap<>();
        item.put("type", artifact.getType().getId());
        item.put("id", artifact.getName() + ":" + artifact.getVersion());
        item.put("name", artifact.getName());
        item.put("version", artifact.getVersion());
        item.put("url", artifact.getUrl());
        return item;
    }

    private Artifact getArtifactFromInstallForm(final InstallForm form) {

        assertEquals(childProject.getParentArtifact().getVersion(), "1");
        assertNotNull(childProject.getParent());
        assertEquals(childProject.getParent().getVersion(), "1");
        assertNotNull(childProject.getModel().getParent());
        assertEquals(childProject.getModel().getParent().getVersion(), "[1,10]");
    }

    /**

        result = 31 * result + a.getGroupId().hashCode();
        result = 31 * result + a.getArtifactId().hashCode();
        result = 31 * result + a.getType().hashCode();
        if (a.getVersion() != null) {
            result = 31 * result + a.getVersion().hashCode();
        }
        result = 31 * result + (a.getClassifier() != null ? a.getClassifier().hashCode() : 0);

        MavenSession session = legacySupport.getSession();

        if (plugin.getVersion() == null) {
            PluginVersionRequest versionRequest = new DefaultPluginVersionRequest(
                    plugin, session.getRepositorySession(), project.getRemotePluginRepositories());
            plugin.setVersion(pluginVersionResolver.resolve(versionRequest).getVersion());
        }

        try {

        Artifact artifact = new DefaultArtifact(
                dependency.getGroupId(),
                dependency.getArtifactId(),
                dependency.getVersion(),
                dependency.getScope(),
                dependency.getType(),
                dependency.getClassifier(),
                new TestArtifactHandler(dependency.getType()));

        return getService(VersionResolver.class).resolve(this, artifact).getVersion();
    }

    @Override
    public List<Version> resolveVersionRange(ArtifactCoordinate artifact) {
        return getService(VersionRangeResolver.class).resolve(this, artifact).getVersions();
    }

    @Override
    public Type requireType(String id) {

                .getOrDefault(artifact.getArtifactId(), Collections.emptyMap())
                .values()
                .stream()
                .map(MavenProject::getVersion)
                .collect(Collectors.collectingAndThen(Collectors.toList(), Collections::unmodifiableList));
        if (!versions.isEmpty()) {
            return versions;
        }
        return getAllProjects()