<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;

    }

    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>

                "'profiles.profile[pro].repositories.repository.id' must be unique"
                        + " but found duplicate repository with id test");
    }

    @Test
    void testValidateUniqueProxyId() throws Exception {
        Settings settings = new Settings();
        Proxy proxy = new Proxy();
        String id = "foo";
        proxy.setId(id);
        proxy.setHost("www.example.com");

    }

    /**
     * @return the model id as {@code groupId:artifactId:packaging:version}
     */
    public String getId() {
        StringBuilder id = new StringBuilder( 64 );

        id.append( ( getGroupId() == null ) ? "[inherited]" : getGroupId() );
        id.append( ":" );
        id.append( getArtifactId() );
        id.append( ":" );
        id.append( getPackaging() );
        id.append( ":" );

        public Optional<Lifecycle> lookup(String id) {
            return Optional.empty();
        }
    };

    private static final PackagingRegistry emptyPackagingRegistry = new PackagingRegistry() {
        @Override
        public Optional<Packaging> lookup(String id) {
            return Optional.of(new Packaging() {
                @Override
                public String id() {
                    return id;
                }