DefaultProblemCollector collector = new DefaultProblemCollector(null);

        collector.add(null, "PROBLEM1", -1, -1, null);

        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());

     */
    Exception getException();

    /**
     * Gets the message that describes this problem.
     *
     * @return The message describing this problem, never {@code null}.
     */
    String getMessage();

    /**
     * Gets the severity level of this problem.
     *
     * @return The severity level of this problem, never {@code null}.
     */

     */
    public ToolchainsBuildingException(List<Problem> problems) {
        super(toMessage(problems));

        this.problems = new ArrayList<>();
        if (problems != null) {
            this.problems.addAll(problems);
        }
    }

    /**
     * Gets the problems that caused this exception.
     *
     * @return The problems that caused this exception, never {@code null}.
     */

        }

        return toolchains;
    }

    private boolean hasErrors(List<Problem> problems) {
        if (problems != null) {
            for (Problem problem : problems) {
                if (Problem.Severity.ERROR.compareTo(problem.getSeverity()) >= 0) {
                    return true;
                }
            }
        }

        return false;
    }

     *
     * @param severity the severity level to get problems for
     * @return a stream of problems with the specified severity
     */
    @Nonnull
    Stream<P> problems(BuilderProblem.Severity severity);

    /**
     * Creates an "empty" problem collector that doesn't store any problems.
     *
     * @param <P> the type of problem
     * @return an empty problem collector
     */
    @Nonnull

    }

    public void add(ModelProblem problem) {
        problems.add(problem);

        severities.add(problem.getSeverity());
    }

    public void addAll(List<ModelProblem> problems) {
        this.problems.addAll(problems);

        for (ModelProblem problem : problems) {
            severities.add(problem.getSeverity());
        }
    }

    @Override

    }

    @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) {
        Problem problem = new DefaultProblem(message, severity, source, line, column, cause);

        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();
        assertEquals(2, problems.size(), "Should collect both problems");
        assertEquals(Problem.Severity.ERROR, problems.get(0).getSeverity(), "First problem should be ERROR");

            file.forEachLine(Charsets.UTF_8) {
                val (version, _, problem, relativePath, lineNumber) = it.split(';')
                byCategory.getOrPut(toCategory(version, file.nameWithoutExtension)) {
                    mutableMapOf()
                }.getOrPut(file.nameWithoutExtension) {
                    mutableSetOf()
                }.add(Problem(name = problem, relativePath = relativePath, lineNumber = lineNumber.toInt()))
            }

     * @param line The one-based index of the line containing the problem or {@code -1} if unknown.
     * @param column The one-based index of the column containing the problem or {@code -1} if unknown.
     * @param cause The cause of the problem, may be {@code null}.
     */
    void add(Problem.Severity severity, String message, int line, int column, Exception cause);

    /**