assertNotNull(collector.getProblems());
        assertEquals(0, collector.getProblems().size());

        collector.add(null, "MESSAGE1", -1, -1, null);

        Exception e2 = new Exception();
        collector.add(Severity.WARNING, null, 42, 127, e2);

        assertEquals(2, collector.getProblems().size());

        Problem p1 = collector.getProblems().get(0);

        ProblemCollector collector2 = ProblemCollectorFactory.newInstance(Collections.singletonList(problem));

        assertNotSame(collector1, collector2);
        assertEquals(0, collector1.getProblems().size());
        assertEquals(1, collector2.getProblems().size());
    }

    @Test
    void testAddProblem() {
        ProblemCollector collector = ProblemCollectorFactory.newInstance(null);
        collector.setSource("pom.xml");

     *
     * @param source a source
     */
    void setSource(String source);

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

     *
     * @return the problems that were encountered during the project building, can be empty but never {@code null}
     */
    @Nonnull
    Collection<BuilderProblem> getProblems();

    /**
     * Gets the result of the dependency resolution for the project.
     *
     * @return the result of the dependency resolution for the project
     */
    @Nonnull

    private String source;

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

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

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

    @Override

            if (cause instanceof ModelBuildingException modelBuildingException) {
                StringBuilder message = new StringBuilder("In: " + pom + "\n\n");
                for (ModelProblem problem : modelBuildingException.getProblems()) {
                    message.append(problem).append("\n");
                }
                System.out.println(message);
                fail(message.toString());
            }

            throw e;

     *
     * @return the problems that were encountered during the settings building, can be empty but never {@code null}
     */
    @Nonnull
    ProblemCollector<BuilderProblem> getProblems();

     *
     * @return the problems that were encountered during the settings building, can be empty but never {@code null}
     */
    @Nonnull
    ProblemCollector<BuilderProblem> getProblems();