assertInstanceOf(Sources.ResolvedPathSource.class, source);
        assertNull(source.getPath());
        assertEquals(path.toString(), source.getLocation());
        assertEquals(modelId, source.getModelId());
    }

    @Test
    void testPathSourceFunctionality() {
        // Test basic source functionality
        Path path = Paths.get("/tmp");

     */
    public static String formatLocation(ModelProblem problem, String projectId) {
        StringBuilder buffer = new StringBuilder(256);

        if (!problem.getModelId().equals(projectId)) {
            buffer.append(problem.getModelId());

            if (!problem.getSource().isEmpty()) {
                if (!buffer.isEmpty()) {
                    buffer.append(", ");
                }

    /**
     * Get the identifier of the POM in the format {@code
     * <groupId>:<artifactId>:<version>}.
     *
     * @return String
     */
    public String getModelId() {
        return this.modelId;
    } // -- String getModelId()

    /**
     * Set the path/URL of the POM or {@code null} if unknown.
     *
     * @param location
     */
    public void setLocation(String location) {

    @Test
    void testBuildSourceHasNoModelId() {
        Path path = Paths.get("/tmp/pom.xml");
        ModelSource source = Sources.buildSource(path);

        assertNotNull(source);
        assertNull(source.getModelId(), "Build sources should not have a modelId");
        assertEquals(path, source.getPath());
    }

    @Test
    void testResolvedSourceWithModelId() {
        String location = "/tmp/resolved-pom.xml";

    @Nullable
    InputStream getInputStream();

    @Nullable
    Reader getReader();

    @Nullable
    Transformer getTransformer();

    boolean isStrict();

    @Nullable
    String getModelId();

    @Nullable
    String getLocation();

    boolean isAddDefaultEntities();

    interface Transformer {
        /**
         * Interpolate the value read from the xml document
         *

            if (req.getLocation().getSource() != null) {
                modelId = req.getLocation().getSource().getModelId();
                source = req.getLocation().getSource().getLocation();
            }
        }

        if (modelId == null) {
            modelId = getModelId();
            source = getSource();
        }

            }
        }
        assertNotNull(dependencyLocation, "missing dependency");
        assertEquals(
                "org.apache.maven.its:bom:0.1", dependencyLocation.getSource().getModelId());

        InputLocation pluginLocation = null;
        for (Plugin plugin : project.getBuildPlugins()) {
            if (plugin.getKey().equals("org.apache.maven.plugins:maven-clean-plugin")) {

     * exception is thrown so this information is merely meant to assist the user.
     *
     * @return The identifier of the POM or an empty string if not known, never {@code null}.
     */
    public String getModelId() {
        if (result == null) {
            return "";
        } else if (result.getEffectiveModel() != null) {
            return result.getEffectiveModel().getId();
        } else if (result.getRawModel() != null) {

                        if (result == null || result.getEffectiveModel() == null) {
                            throw new ProjectBuildingException(
                                    e.getModelId(), e.getMessage(), pomFile != null ? pomFile.toFile() : null, e);
                        }
                        // validation error, continue project building and delay failing to help IDEs
                        error = e;

     *
     * @return the model identifier, or {@code null} if not available or not applicable
     * @since 4.0.0
     */
    @Nullable
    default String getModelId() {
        return null;
    }

    /**
     * Interface for locating POM files within a project structure.
     * Implementations of this interface provide the ability to find POM files