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

                res.getIncidentEdges(v2).get(0).getVersion(),
                "wrong edge v1-v2 in the resulting graph after resolver");

        assertEquals(
                1, res.getIncidentEdges(v3).size(), "wrong # of edges v1-v3 in the resulting graph after resolver");
        assertEquals(
                "1.1",
                res.getIncidentEdges(v3).get(0).getVersion(),

     */
    @Nonnull
    Version getVersion();

    /**
     * {@return the version or meta-version of the artifact}.
     * A meta-version is a version suffixed with the {@code SNAPSHOT} keyword.
     * Meta-versions are represented in a base version by their symbols (e.g., {@code SNAPSHOT}),
     * while they are replaced by, for example, the actual timestamp in the {@linkplain #getVersion() version}.
     */
    @Nonnull

        assertEquals(createSet(artifacts), res.getArtifacts(), "Check artifact list");
        assertEquals("1.0", getArtifact("d", res.getArtifacts()).getVersion(), "Check version");
        assertEquals("2.0", getArtifact("b", res.getArtifacts()).getVersion(), "Check version");
    }

    @Test
    void testResolveNearestNewestIsNearest() throws ArtifactResolutionException, InvalidVersionSpecificationException {

        assertEquals("fess-crawler-smbj", list.get(0).getName());
        assertEquals("14.14.0", list.get(0).getVersion());
        assertEquals("plugin/repo3/fess-crawler-smbj/14.14.0/fess-crawler-smbj-14.14.0.jar", list.get(0).getUrl());
        assertEquals("fess-crawler-smbj", list.get(1).getName());
        assertEquals("14.15.0", list.get(1).getVersion());

            SnapshotVersion sv = new SnapshotVersion();
            sv.setClassifier(artifact.getClassifier());
            sv.setExtension(artifact.getExtension());
            sv.setVersion(getVersion());
            sv.setUpdated(lastUpdated);
            versions.put(getKey(sv.getClassifier(), sv.getExtension()), sv);
        }

        Versioning versioning = recessive.getVersioning();

        return this.groupId;
    } // -- String getGroupId()

    /**
     * Get the version of the extension.
     *
     * @return String
     */
    public String getVersion() {
        return this.version;
    } // -- String getVersion()

    /**
     * Set the artifact ID of the extension.
     *
     * @param artifactId a artifactId object.
     */
    public void setArtifactId(String artifactId) {

        metadata.setArtifactId(artifact.getArtifactId());
        metadata.setVersion(artifact.getBaseVersion());

        return metadata;
    }

    public void bind(Artifact artifact) {
        artifacts.add(artifact);
    }

    public Object getKey() {
        return getGroupId() + ':' + getArtifactId() + ':' + getVersion();
    }

    public static Object getKey(Artifact artifact) {

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

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

        if (empty(type)) {

        return artifactId;
    }

    public void setArtifactId(String artifactId) {
        this.artifactId = artifactId;
    }

    public String getVersion() {
        return version;
    }

    public void setVersion(String version) {
        this.version = version;
    }

    public String getClassifier() {
        return classifier;
    }