*
     * @return the message describing this problem, never {@code null}
     */
    @Nonnull
    String getMessage();

    /**
     * Gets the severity level of this problem.
     *
     * @return the severity level of this problem, never {@code null}
     */
    @Nonnull
    Severity getSeverity();

    /**
     * The different severity levels for a problem, in decreasing order.
     *

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

/**
 * Base class for requests.
 *
 * @since 4.0.0
 */
@Experimental
abstract class BaseRequest {

    private final Session session;

    protected BaseRequest(@Nonnull Session session) {
        this.session = nonNull(session, "session cannot be null");
    }

    @Nonnull
    public Session getSession() {
        return session;

      Class<? super @NonNull E> type, E[] emptyArrayForContents, Iterable<? extends E> contents) {
    List<E> setContents = new ArrayList<>();
    for (E e : contents) {
      if (!setContents.contains(e)) {
        setContents.add(e);
      }
    }
    return new MinimalSet<>(type, setContents.toArray(emptyArrayForContents));
  }

  private MinimalSet(Class<? super @NonNull E> type, E... contents) {

     * @throws IllegalArgumentException if an argument is {@code null} or invalid
     */
    default void deploy(
            @Nonnull Session session,
            @Nonnull RemoteRepository repository,
            @Nonnull Collection<ProducedArtifact> artifacts) {
        deploy(ArtifactDeployerRequest.build(session, repository, artifacts));
    }

     *
     * @return file paths to place on the different tool options
     */
    @Nonnull
    Map<PathType, List<Path>> getDispatchedPaths();

    /**
     * {@return all dependencies associated to their paths}
     * Some dependencies may be associated to a null value if there is no path available.
     */
    @Nonnull
    Map<Dependency, Path> getDependencies();

    /**

   */
  @CheckForNull
  <T extends @NonNull B> T getInstance(Class<T> type);

  /**
   * Returns the value the specified type is mapped to, or {@code null} if no entry for this type is
   * present. This will only return a value that was bound to this specific type, not a value that
   * may have been bound to a subtype.
   */
  @CheckForNull
  <T extends @NonNull B> T getInstance(TypeToken<T> type);

  /**

   */
  @CheckForNull
  <T extends @NonNull B> T getInstance(Class<T> type);

  /**
   * Returns the value the specified type is mapped to, or {@code null} if no entry for this type is
   * present. This will only return a value that was bound to this specific type, not a value that
   * may have been bound to a subtype.
   */
  @CheckForNull
  <T extends @NonNull B> T getInstance(TypeToken<T> type);

  /**

     * create a custom {@code Type} for it.
     *
     * @param id the id of the type to retrieve
     * @return the type
     */
    @Nonnull
    @Override
    default Type require(@Nonnull String id) {
        return lookup(id).orElseThrow(() -> new IllegalArgumentException("Unknown extensible enum value '" + id + "'"));
    }

      Class<? super @NonNull E> type, E... contents) {
    return new MinimalCollection<>(type, true, contents);
  }

  private final E[] contents;
  private final Class<? super @NonNull E> type;
  private final boolean allowNulls;

  // Package-private so that it can be extended.
  MinimalCollection(Class<? super @NonNull E> type, boolean allowNulls, E... contents) {

 * @see ModelBase#getRepositories()
 * @see ModelBase#getPluginRepositories()
 */
@Experimental
@Immutable
public interface RemoteRepository extends Repository {

    @Nonnull
    String getUrl();

    @Nonnull
    String getProtocol();