.groupId(requireNonNull(dependency, "dependency").getGroupId())
                .artifactId(dependency.getArtifactId())
                .version(dependency.getVersion().toString())
                .classifier(dependency.getClassifier())
                .extension(dependency.getExtension())
                .type(dependency.getType().id())
                .scope(dependency.getScope().id())

    }

    private static String getKey(Model model) {
        return "project>" + model.getGroupId() + ":" + model.getArtifactId() + ":" + model.getVersion();
    }

    @Override
    public ClassRealm createExtensionRealm(Plugin plugin, List<Artifact> artifacts) {
        Objects.requireNonNull(plugin, "plugin cannot be null");

    public void setVersion(String version) {
        getModel().setVersion(version);
    }

    public String getVersion() {
        String version = getModel().getVersion();

        if ((version == null) && (getModel().getParent() != null)) {
            version = getModel().getParent().getVersion();
        }

        return version;
    }

    public String getPackaging() {

        Artifact depArtifact = dep1.getArtifact();
        assertEquals("ut.simple", depArtifact.getGroupId());
        assertEquals("dependency", depArtifact.getArtifactId());
        assertEquals("1.0", depArtifact.getVersion());
        assertEquals("1.0", depArtifact.getBaseVersion());
        assertNull(depArtifact.getFile());
        assertFalse(depArtifact.isSnapshot(), "Expected " + depArtifact + ".isSnapshot() to return false");

            changed = true;
        } else {
            changed = metadata.merge(this.metadata);
        }

        // beware meta-versions!
        String version = metadata.getVersion();
        if (Artifact.LATEST_VERSION.equals(version) || Artifact.RELEASE_VERSION.equals(version)) {
            // meta-versions are not valid <version/> values...don't write them.
            metadata.setVersion(null);

    }

    /**
     * Gets the effective version of the model.
     *
     * @return The effective version of the model or an empty string if unknown, never {@code null}.
     */
    public String getVersion() {
        return (version != null) ? version : "";
    }

    /**
     * Sets the effective version of the model.
     *
     * @param version The effective version of the model, may be {@code null}.

        when(artifact.getArtifactId()).thenReturn("artifact1");
        when(artifact.getExtension()).thenReturn("ext");
        when(artifact.getClassifier()).thenReturn("classifier1");
        when(artifact.getVersion()).thenReturn("1");
        artifacts.add(artifact);

        Artifact artifact2 = mock(Artifact.class);
        when(artifact2.getFile()).thenReturn(null);
        when(artifact2.getGroupId()).thenReturn("group1");

     */
    String getClassifier();

    /**
     * Gets the version of the constituent's artifact.
     *
     * @return The version, never {@code null}.
     */
    String getVersion();

    /**
     * Gets the file of the constituent's artifact.
     *
     * @return The file, never {@code null}.
     */
    File getFile();

                Plugin existing = plugins.get(plugin);
                if (existing != null) {
                    if (existing.getVersion() == null) {
                        existing.setVersion(plugin.getVersion());
                        existing.setLocation("version", location);
                    }
                    plugin = existing;
                } else {

        CoreExtension oldExtension = new CoreExtension();
        oldExtension.setGroupId(extension.getGroupId());
        oldExtension.setArtifactId(extension.getArtifactId());
        oldExtension.setVersion(extension.getVersion());
        if (extension.getClassLoadingStrategy() != null) {
            oldExtension.setClassLoadingStrategy(extension.getClassLoadingStrategy());
        }
        this.extension = oldExtension;
    }