* @param options The options to use for deserialization, may be {@code null} to use the default values.
     * @return The deserialized metadata, never {@code null}.
     * @throws IOException If the metadata could not be deserialized.
     * @throws MetadataParseException If the input format could not be parsed.
     */

     * artifact files.
     *
     * @param session the {@link Session}, must not be {@code null}
     * @param root the Maven Dependency, must not be {@code null}
     * @return the collection result, never {@code null}
     * @throws DependencyCollectorException if the dependency tree could not be built
     * @throws IllegalArgumentException if an argument is null or invalid

     * OS family that can be tested for. {@value}
     */
    private static final String FAMILY_OS2 = "os/2";

    /**
     * OS family that can be tested for. {@value}
     */
    private static final String FAMILY_NETWARE = "netware";

    /**
     * OS family that can be tested for. {@value}
     */
    private static final String FAMILY_DOS = "dos";

    /**
     * OS family that can be tested for. {@value}
     */

     * {@link org.apache.maven.model.ConfigurationContainer#getConfiguration()} or a similar source.
     * If {@code element} is not {@code null}, child configuration element with the specified name will
     * be unmarshalled.
     *
     * @param configuration The configuration to unmarshal, may be {@code null}.

 * <p>
 * Unlike a cache, this session data is not subject to purging. For this same reason, session data should also not be
 * abused as a cache (i.e. for storing values that can be re-calculated) to avoid memory exhaustion.
 * <p>
 * <strong>Note:</strong> Actual implementations must be thread-safe.
 *
 * @see Session#getData()
 * @since 4.0.0
 */
@Experimental
@ThreadSafe
@Provider

     * for technical reasons, it is not part of the public API. In particular, this method can be changed or deleted
     * without prior notice and must not be used by plugins.
     *
     * @param classRealm The class realm hosting the build extensions of this project, may be {@code null}.
     */
    public void setClassRealm(ClassRealm classRealm) {
        this.classRealm = classRealm;
    }

     * @param pluginGroups The list of group ids to scan for the plugin prefix, may be {@code null}.
     * @return This request, never {@code null}.
     */
    PluginPrefixRequest setPluginGroups(List<String> pluginGroups);

    /**
     * Gets the POM whose build plugins are to be scanned for the prefix.
     *
     * @return The POM whose build plugins are to be scanned for the prefix or {@code null} to only search the plugin

     * If no module is found, or if module information cannot be extracted, then this constructor
     * builds an empty map.
     *
     * <p>If the {@code resolve} parameter value is {@code false}, then some or all map values may
     * be null instead of the actual module name. This option can avoid the cost of reading module
     * descriptors when only the modules existence needs to be verified.</p>
     *
     * <p><b>Algorithm:</b>

        return builder()
                .session(nonNull(session, "session cannot be null"))
                .repository(nonNull(repository, "repository cannot be null"))
                .artifacts(nonNull(artifacts, "artifacts cannot be null"))
                .build();
    }

    class ArtifactDeployerRequestBuilder {
        Session session;

// TODO what runs in each phase
// TODO plugins that need downloading
// TODO project dependencies that need downloading
// TODO unfortunately the plugins need to be downloaded in order to get the plugin.xml file. need to externalize this
//      from the plugin archive.
// TODO this will be the class that people get in IDEs to modify

/**
 * MavenExecutionPlan
 */
public class MavenExecutionPlan implements Iterable<ExecutionPlanItem> {