*
 * Implementation must have {@code equals()} and {@code hashCode()} implemented, so implementations of this interface
 * can be used as keys.
 *
 * @since 4.0.0
 */
@Experimental
public interface ExtensibleEnum {

    /**
     * The {@code id} uniquely represents a value for this extensible enum.
     * This id should be used to compute the equality and hash code for the instance.
     *
     * @return the id
     */

 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.maven.api.spi;

import java.util.Collection;

import org.apache.maven.api.ExtensibleEnum;
import org.apache.maven.api.annotations.Consumer;
import org.apache.maven.api.annotations.Experimental;
import org.apache.maven.api.annotations.Nonnull;

/**
 * An SPI interface to extend Maven with a new enum value.

 * under the License.
 */
package org.apache.maven.api.services;

import java.util.Optional;

import org.apache.maven.api.ExtensibleEnum;
import org.apache.maven.api.Service;
import org.apache.maven.api.annotations.Nonnull;

public interface ExtensibleEnumRegistry<T extends ExtensibleEnum> extends Service {
    @Nonnull
    Optional<T> lookup(@Nonnull String id);

    @Nonnull
    default T require(@Nonnull String id) {

 * can be used as keys.
 *
 * @since 4.0.0
 */
@Experimental
@Immutable
@SuppressWarnings("checkstyle:InterfaceIsType")
public interface Language extends ExtensibleEnum {

    /**
     * The "none" language. It is not versioned, family is same to itself, and compatible with itself only.
     * In turn, every {@link Language} implementation must be compatible with {@code NONE} language.

 * can be used as keys.
 *
 * @since 4.0.0
 */
@Experimental
@Immutable
@SuppressWarnings("checkstyle:InterfaceIsType")
public interface ProjectScope extends ExtensibleEnum {

    /**
     * Main scope.
     */
    ProjectScope MAIN = projectScope("main");

    /**
     * Test scope.
     */
    ProjectScope TEST = projectScope("test");

 * @see org.apache.maven.api.Project#getPackaging()
 * @see org.apache.maven.api.model.Model#getPackaging()
 * @since 4.0.0
 */
@Experimental
@Immutable
public interface Packaging extends ExtensibleEnum {
    /**
     * The packaging id.
     */
    @Nonnull
    String id();

    /**
     * The language of this packaging.
     */
    @Nonnull
    default Language language() {

    }

    static ProjectScope projectScope(String id) {
        return new DefaultProjectScope(id);
    }

    private static class DefaultExtensibleEnum implements ExtensibleEnum {

        private final String id;

        DefaultExtensibleEnum(String id) {
            this.id = Objects.requireNonNull(id);
        }

        public String id() {
            return id;

 * can be used as keys.
 *
 * @since 4.0.0
 * @see org.apache.maven.api.services.DependencyResolver
 * @see DependencyScope
 */
@Experimental
@Immutable
public interface PathScope extends ExtensibleEnum {

    // TODO: what if I simply want all dependencies ?
    @Nonnull
    ProjectScope projectScope();

    @Nonnull
    Set<DependencyScope> dependencyScopes();

    PathScope MAIN_COMPILE = pathScope(

 * {@code default} lifecycle being the most commonly used for project builds.
 *
 * @since 4.0.0
 */
@Experimental
@Immutable
public interface Lifecycle extends ExtensibleEnum {

    // =========================
    // Maven defined lifecycles
    // =========================
    String CLEAN = "clean";
    String DEFAULT = "default";
    String SITE = "site";

 * {@code sources} classifier. The artifact and its dependencies should be added
 * to the build path.
 *
 * @since 4.0.0
 */
@Experimental
@Immutable
public interface Type extends ExtensibleEnum {
    /**
     * Artifact type name for a POM file.
     */
    String POM = "pom";

    /**
     * Artifact type name for a BOM file.
     */
    String BOM = "bom";

    /**