<id>extension</id>
  <name>ExtensionDescriptor</name>
  <description><![CDATA[
    Extension descriptor, stored in <code>META-INF/maven/extension.xml</code> in an extension's jar artifact to
    precisely control parts of the extension and dependencies to expose in the API class loader.

     * same class realm is used to load build extensions and load mojos for extensions=true plugins.
     * </p>
     * <strong>Note:</strong> This is part of internal implementation and may be changed or removed without notice
     *
     * @since 3.3.0
     */
    public static final String KEY_EXTENSIONS_REALMS = DefaultMavenPluginManager.class.getName() + "/extensionsRealms";

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * A type implemented by, or extended by maven plugins or extensions.
 * Maven plugins or extensions may provide implementations of those types which will be used by maven.
 * <p>
 * A type can be marked {@link Consumer} or {@link Provider} but not both. A type is assumed to be

// CHECKSTYLE_OFF: RegexpHeader
/**
 * <a href="https://maven.apache.org/resolver/">Maven Resolver</a> extensions for utilizing the Maven POM and Maven
 * repository metadata.
 */

    }

    private static String getKey(Plugin plugin, boolean extension) {
        String version = ArtifactUtils.toSnapshotVersion(plugin.getVersion());
        return (extension ? "extension>" : "plugin>") + plugin.getGroupId() + ":" + plugin.getArtifactId() + ":"
                + version;
    }

                          echo "Checkout ITs from branch: ${ITS_BRANCH}"
                          checkout([$class: 'GitSCM',
                                  branches: [[name: ITS_BRANCH]],
                                  extensions: [[$class: 'CloneOption', depth: 1, noTags: true, shallow: true]],
                                  userRemoteConfigs: [[url: 'https://github.com/apache/maven-integration-testing.git']]])

        if (lookup == null) {
            return customLifecycles != null ? customLifecycles : new HashMap<>();
        }

        // Lifecycles cannot be cached as extensions might add custom lifecycles later in the execution.
        try {
            Map<String, Lifecycle> lifecycles = new HashMap<>(lookup.lookupMap(Lifecycle.class));
            for (org.apache.maven.api.Lifecycle lf : registry) {

        PomTestWrapper pom = buildPom("build-extension-inheritance/sub");
        assertEquals(3, ((List<?>) pom.getValue("build/extensions")).size());
        assertEquals("b", pom.getValue("build/extensions[1]/artifactId"));
        assertEquals("a", pom.getValue("build/extensions[2]/artifactId"));
        assertEquals("0.2", pom.getValue("build/extensions[2]/version"));

        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();

          </description>
          <type>String</type>
        </field>
        <field>
          <name>extensions</name>
          <version>4.0.0+</version>
          <description>A set of build extensions to use from this project.</description>
          <association>
            <type>Extension</type>
            <multiplicity>*</multiplicity>
          </association>
        </field>
      </fields>