this.classifier = classifier;
            return this;
        }

        public DependencyCoordinatesFactoryRequestBuilder extension(String extension) {
            this.extension = extension;
            return this;
        }

        public DependencyCoordinatesFactoryRequestBuilder type(String type) {
            this.type = type;
            return this;

            <multiplicity>*</multiplicity>
          </association>
        </field>
      </fields>
    </class>
    <class xml.tagName="extension">
      <name>CoreExtension</name>
      <description>Describes a build extension to utilise.</description>
      <version>1.0.0+</version>
      <fields>
        <field>
          <name>groupId</name>

  <build>
    <!-- project extensions should precede inherited extensions -->
    <extensions>
      <extension>
        <groupId>org.apache.maven.its.mng3899</groupId>
        <artifactId>b</artifactId>
        <version>0.1</version>
      </extension>
      <extension>
        <!-- project extensions should override inherited extension with equal gid:aid -->
        <groupId>org.apache.maven.its.mng3899</groupId>

import org.apache.maven.execution.scope.internal.MojoExecutionScope;
import org.apache.maven.execution.scope.internal.MojoExecutionScopeModule;
import org.apache.maven.extension.internal.CoreExports;
import org.apache.maven.extension.internal.CoreExtensionEntry;
import org.apache.maven.internal.impl.DefaultLookup;
import org.apache.maven.session.scope.internal.SessionScope;

        plugin.setVersion(version);
        return plugin;
    }

    private Extension createExtension(String groupId, String artifactId, String version) {
        Extension extension = new Extension();
        extension.setGroupId(groupId);
        extension.setArtifactId(artifactId);
        extension.setVersion(version);
        return extension;
    }

        if (build != null) {
            for (Extension extension : build.getExtensions()) {
                Plugin plugin = new Plugin();
                plugin.setGroupId(extension.getGroupId());
                plugin.setArtifactId(extension.getArtifactId());
                plugin.setVersion(extension.getVersion());
                XmlNode configuration = extension.getDelegate().getConfiguration();

    private final CoreExtensionEntry extension;
    private final UnaryOperator<String> callback;
    private final DefaultInterpolator interpolator = new DefaultInterpolator();

    public ExtensionConfigurationModule(CoreExtensionEntry extension, UnaryOperator<String> callback) {
        this.extension = extension;
        this.callback = callback;
    }

    @Override

    }

    private CoreExtensionEntry createExtension(CoreExtension extension, List<Artifact> artifacts) throws Exception {
        String realmId = "coreExtension>" + extension.getGroupId() + ":" + extension.getArtifactId() + ":"
                + extension.getVersion();
        final ClassRealm realm = classWorld.newRealm(realmId, null);
        Set<String> providedArtifacts = Collections.emptySet();

    private final CoreExtensionEntry extension;
    private final UnaryOperator<String> callback;

    private final DefaultInterpolator interpolator = new DefaultInterpolator();

    public ExtensionConfigurationModule(CoreExtensionEntry extension, UnaryOperator<String> callback) {
        this.extension = extension;
        this.callback = callback;
    }

    @Override

        for (CoreExtension extension : configuration) {
            List<Artifact> artifacts =
                    resolveExtension(extension, repoSession, repositories, dependencyFilter, interpolator);
            if (!artifacts.isEmpty()) {
                extensions.add(new LoadedCoreExtension(extension, createExtension(extension, artifacts)));
            }
        }