}

    /**
     * @return the model id as {@code groupId:artifactId:packaging:version}
     */
    public String getId() {
        StringBuilder id = new StringBuilder( 64 );

        id.append( ( getGroupId() == null ) ? "[inherited]" : getGroupId() );
        id.append( ":" );
        id.append( getArtifactId() );
        id.append( ":" );
        id.append( getPackaging() );
        id.append( ":" );

        <version>2.1-SNAPSHOT</version>
        <executions>
          <execution>
            <!-- NOTE: Explicitly reference "default" id here -->
            <id>default</id>
            <phase>child-default</phase>
          </execution>
          <execution>
            <id>non-default</id>
            <phase>child-non-default</phase>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>

        public Optional<Lifecycle> lookup(String id) {
            return Optional.empty();
        }
    };

    private static final PackagingRegistry emptyPackagingRegistry = new PackagingRegistry() {
        @Override
        public Optional<Packaging> lookup(String id) {
            return Optional.of(new Packaging() {
                @Override
                public String id() {
                    return id;
                }

    }

    /**
     * Gets the group id of the unresolvable model.
     *
     * @return The group id of the unresolvable model, can be empty but never {@code null}.
     */
    public String getGroupId() {
        return groupId;
    }

    /**
     * Gets the artifact id of the unresolvable model.
     *
     * @return The artifact id of the unresolvable model, can be empty but never {@code null}.

 */
public class Lifecycle {
    /**
     * Field id
     */
    private String id;

    /**
     * Field phases
     */
    private Map<String, LifecyclePhase> lifecyclePhases;

    /**
     * Method getId
     */
    public String getId() {
        return this.id;
    }

    /**
     * Method getLifecyclePhases

    POM has a non-empty element and the child POM has an empty element to join.
  </description>

  <properties>
    <prop0>test</prop0>
  </properties>

  <repositories>
    <repository>
      <id>equal-repo-id</id>
      <url>https://maven.apache.org/null</url>
      <snapshots>
        <enabled>false</enabled>
      </snapshots>
      <releases>
        <checksumPolicy>ignore</checksumPolicy>
      </releases>

import javax.inject.Named;
import javax.inject.Singleton;

/**
 * {@code wrapper} lifecycle provider.
 */
@Named(WrapperLifecycleProvider.LIFECYCLE_ID)
@Singleton
public final class WrapperLifecycleProvider extends AbstractLifecycleProvider {
    static final String LIFECYCLE_ID = "wrapper";

    // START SNIPPET: wrapper
    private static final String[] PHASES = {"wrapper"};

import javax.inject.Named;
import javax.inject.Singleton;

/**
 * {@code clean} lifecycle provider.
 */
@Named(CleanLifecycleProvider.LIFECYCLE_ID)
@Singleton
public final class CleanLifecycleProvider extends AbstractLifecycleProvider {
    static final String LIFECYCLE_ID = "clean";

    // START SNIPPET: clean
    private static final String[] PHASES = {"pre-clean", "clean", "post-clean"};

    /**
     * Obtain the {@link Type} from the specified {@code id}.
     * <p>
     * Shortcut for {@code getService(TypeRegistry.class).require(...)}.
     *
     * @see org.apache.maven.api.services.TypeRegistry#require(String)
     */
    @Nonnull
    Type requireType(@Nonnull String id);

    /**
     * Obtain the {@link Language} from the specified {@code id}.
     * <p>

     * <syntax>project.distributionManagementArtifactRepository</syntax>
     * <origin><![CDATA[
     * <distributionManagement>
     * <repository>
     * <id>some-repo</id>
     * <url>scp://host/path</url>
     * </repository>
     * <snapshotRepository>
     * <id>some-snap-repo</id>
     * <url>scp://host/snapshot-path</url>
     * </snapshotRepository>
     * </distributionManagement>
     * ]]></origin>
     * <usage><![CDATA[