<developer>
      <id>rdonkin</id>
      <name>Robert Burrell Donkin</name>
      <email>rdonkin at apache dot org</email>
      <organization>Apache Software Foundation</organization>
    </developer>
    <developer>
      <id>donaldp</id>
      <name>Peter Donald</name>
      <email>donaldp at apache dot org</email>
      <organization></organization>
    </developer>
    <developer>
      <id>costin</id>

    /**
     * Obtain the {@link Type} from the specified {@code id}.
     * If no type is known for {@code id}, the registry will
     * 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) {

    }

    protected Artifact createArtifact(String id, String version) throws InvalidVersionSpecificationException {
        return createArtifact(id, version, Artifact.SCOPE_COMPILE);
    }

    protected Artifact createArtifact(String id, String version, String scope)
            throws InvalidVersionSpecificationException {
        return createArtifact(id, version, scope, null, false);
    }

     * Create a key using the given class and id.
     */
    static <T> Key<T> key(Class<T> clazz, Object id) {
        return new Key<>(clazz, id);
    }

    /**
     * Key used to query the session data
     * @param <T> the type of the object associated to this key
     */
    final class Key<T> {

        private final Class<T> type;
        private final Object id;

    String ROLE = ArtifactRepositoryFactory.class.getName();

    String DEFAULT_LAYOUT_ID = "default";

    String LOCAL_REPOSITORY_ID = "local";

    @Deprecated
    ArtifactRepositoryLayout getLayout(String layoutId) throws UnknownRepositoryLayoutException;

    @Deprecated
    ArtifactRepository createDeploymentArtifactRepository(String id, String url, String layoutId, boolean uniqueVersion)

    }

    private void getDownstreamProjects(String projectId, Set<String> projectIds, boolean transitive) {
        for (String id : sorter.getDependents(projectId)) {
            if (projectIds.add(id) && transitive) {
                getDownstreamProjects(id, projectIds, transitive);
            }
        }
    }

    public List<MavenProject> getUpstreamProjects(MavenProject project, boolean transitive) {

            String id = repo.getId();

            if (id == null || id.isEmpty()) {
                throw new InvalidRepositoryException("Repository identifier missing", "");
            }

            String url = repo.getUrl();

            if (url == null || url.isEmpty()) {
                throw new InvalidRepositoryException("URL missing for repository " + id, id);
            }

    }

    private ArtifactSpec createArtifactSpec(String id, String version) throws InvalidVersionSpecificationException {
        return createArtifactSpec(id, version, Artifact.SCOPE_COMPILE);
    }

    private ArtifactSpec createArtifactSpec(String id, String version, boolean optional)
            throws InvalidVersionSpecificationException {
        return createArtifactSpec(id, version, Artifact.SCOPE_COMPILE, null, optional);
    }

     * @return the current offset
     */
    int getCharacterOffset();

    /**
     * Returns the public ID of the XML
     * @return the public ID, or null if not available
     */
    String getPublicId();

    /**
     * Returns the system ID of the XML
     * @return the system ID, or null if not available
     */
    String getSystemId();

    </mailingList>
  </mailingLists>
  <developers>
    <developer>
      <id>jvanzyl</id>
      <name>Jason van Zyl</name>
      <email>******@****.***</email>
      <organization>ASF</organization>
      <roles>
        <role>PMC Chair</role>
      </roles>
      <timezone>-5</timezone>
    </developer>
    <developer>
      <id>brett</id>
      <name>Brett Porter</name>
      <email>******@****.***</email>