* artifact.
 *
 */
@Deprecated
public interface ArtifactMetadataSource {

    ResolutionGroup retrieve(MetadataResolutionRequest request) throws ArtifactMetadataRetrievalException;

    ResolutionGroup retrieve(
            Artifact artifact, ArtifactRepository localRepository, List<ArtifactRepository> remoteRepositories)
            throws ArtifactMetadataRetrievalException;

    /**
     * Gets the super POM for the specified model version.
     *
     * @param version The model version to retrieve the super POM for (e.g. "4.0.0"), must not be {@code null}.
     * @return The super POM, never {@code null}.
     * @throws SuperPomProviderException if the super POM could not be retrieved
     */
    @Nonnull
    Model getSuperPom(@Nonnull String version);

 * It provides API: <ol>
 * <li>to retrieve every toolchains available in user settings,</li>
 * <li>to store chosen toolchain into build context for later use by toolchain-aware plugins.</li>
 * </ol>
 *
 * @since 2.0.9
 * @see ToolchainManager#getToolchainFromBuildContext(String, MavenSession)
 */
public interface ToolchainManagerPrivate {

    /**
     * Retrieves every toolchains of given type available in user settings.

     * responsible for creating a copy of the original data and store the copy in the cache.
     *
     * @param request The repository request from which this cache was retrieved, must not be {@code null}.
     * @param key The key to use associate the data with, must not be {@code null}.
     * @param data The data to store in the cache, may be {@code null}.
     */

        // Metadata cannot be found

        if (result.hasMetadataResolutionExceptions()) {
            throw result.getMetadataResolutionException(0);
        }

        // Metadata cannot be retrieved

        // Cyclic Dependency Error

        if (result.hasCircularDependencyExceptions()) {
            throw result.getCircularDependencyException(0);
        }

        // Version Range Violation

        }
        if (path == null) {
            paths.remove(id);
        } else {
            paths.put(id, path);
        }
    }

    /**
     * Retrieve a stream of the project's artifacts.
     * Do not include the POM artifact as the file can't be set anyway.
     */
    private Stream<org.apache.maven.artifact.Artifact> getProjectArtifacts(MavenProject project) {

    /**
     * Retrieves the descriptor for the specified plugin goal from the plugin's main artifact.
     *
     * @param plugin The plugin whose mojo descriptor should be retrieved, must not be {@code null}.
     * @param goal The simple name of the mojo whose descriptor should be retrieved, must not be {@code null}.

     * indirectly depends on the given project.
     *
     * @param project The project whose downstream projects should be retrieved, must not be {@code null}.
     * @param transitive A flag whether to retrieve all direct and indirect downstream projects or just the immediate
     *            downstream projects.
     * @return The downstream projects in the build order, never {@code null}.

        this.delegate = delegate;
    }

    @Override
    public ResolutionGroup retrieve(MetadataResolutionRequest request) throws ArtifactMetadataRetrievalException {
        return delegate.retrieve(request);
    }

    @Override
    public ResolutionGroup retrieve(
            Artifact artifact, ArtifactRepository localRepository, List<ArtifactRepository> remoteRepositories)

import org.apache.maven.api.annotations.Experimental;
import org.apache.maven.api.annotations.ThreadSafe;

/**
 * Marker interface for all services provided by the {@link Session}.
 * <p>
 * Services can be retrieved from the session using the
 * {@link Session#getService(Class)} method.
 *
 * @since 4.0.0
 * @see Session#getService(Class)
 */
@Experimental
@ThreadSafe