default void add(ModelProblem problem) {
        getProblemCollector().reportProblem(problem);
    }

    ModelBuilderException newModelBuilderException();

    void setSource(String location);

    void setSource(Model model);

    String getSource();

    void setRootModel(Model model);

    Model getRootModel();

        collector.setSource("SOURCE_PROBLEM2");
        collector.add(null, "PROBLEM2", -1, -1, null);

        collector.setSource("SOURCE_PROBLEM3");
        collector.add(null, "PROBLEM3", -1, -1, null);

        assertEquals("", collector.getProblems().get(0).getSource());
        assertEquals("SOURCE_PROBLEM2", collector.getProblems().get(1).getSource());

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

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

        assertEquals(1, collector2.getProblems().size());
    }

    @Test
    void testAddProblem() {
        ProblemCollector collector = ProblemCollectorFactory.newInstance(null);
        collector.setSource("pom.xml");
        collector.add(Problem.Severity.ERROR, "Error message", 10, 5, null);
        collector.add(Problem.Severity.WARNING, "Warning message", 15, 3, null);

        List<Problem> problems = collector.getProblems();

                e.getMessage());
    }

    @Test
    void testUnknownPosition() {
        ProblemCollector problemCollector = ProblemCollectorFactory.newInstance(null);
        problemCollector.setSource("SOURCE");
        problemCollector.add(Problem.Severity.ERROR, "MESSAGE", -1, -1, new Exception());
        ToolchainsBuildingException e = new ToolchainsBuildingException(problemCollector.getProblems());
        assertEquals(

        Settings userSettings = readSettings(userSettingsSource, request, problems);

        settingsMerger.merge(userSettings, globalSettings, TrackableBase.GLOBAL_LEVEL);

        problems.setSource("");

        userSettings = interpolate(userSettings, request, problems);

        // for the special case of a drive-relative Windows path, make sure it's absolute to save plugins from trouble

     * their source, but the next messages will use the new source.
     *
     * @param source a source
     */
    void setSource(String source);

    /**
     *
     * @return the collected Problems, never {@code null}
     */
    List<Problem> getProblems();

        this.problems = (problems != null) ? problems : new ArrayList<>();
    }

    public List<SettingsProblem> getProblems() {
        return problems;
    }

    public void setSource(String source) {
        this.source = source;
    }

    @Override
    public void add(SettingsProblem.Severity severity, String message, int line, int column, Exception cause) {

        this.problems = (problems != null) ? problems : new ArrayList<>();
    }

    @Override
    public List<Problem> getProblems() {
        return problems;
    }

    @Override
    public void setSource(String source) {
        this.source = source;
    }

    @Override
    public void add(Problem.Severity severity, String message, int line, int column, Exception cause) {

        return artifactUri;
    }

    public void setArtifactUri(String artifactUri) {
        this.artifactUri = artifactUri;
    }

    public MetadataGraphVertex getSource() {
        return source;
    }

    public void setSource(MetadataGraphVertex source) {
        this.source = source;
    }

    public MetadataGraphVertex getTarget() {
        return target;
    }