problemCollector.add(Problem.Severity.ERROR, "MESSAGE", 3, 5, new Exception());
        ToolchainsBuildingException e = new ToolchainsBuildingException(problemCollector.getProblems());
        assertEquals(
                "1 problem was encountered while building the effective toolchains" + LS
                        + "[ERROR] MESSAGE @ line 3, column 5" + LS,
                e.getMessage());
    }

        }

        long totalProblems = 0;
        long errorProblems = 0;

        for (ProjectBuildingResult result : results) {
            List<ModelProblem> problems = result.getProblems();
            totalProblems += problems.size();

            for (ModelProblem problem : problems) {
                if (problem.getSeverity() != ModelProblem.Severity.WARNING) {
                    errorProblems++;

                getProblems(problem.getSeverity()).add(problem);
                return true;
            }
            return false;
        }

        @Override
        public Stream<P> problems(BuilderProblem.Severity severity) {
            requireNonNull(severity, "severity");
            return getProblems(severity).stream();
        }

/**
 * Defines events that the model builder fires during construction of the effective model. When a listener encounters
 * errors while processing the event, it can report these problems via {@link ModelBuildingEvent#getProblems()}.
 * Note: To cope with future extensions to this interface, it is strongly recommended to extend
 * {@link AbstractModelBuildingListener} rather than to directly implement this interface.
 *

        assertNotNull(actual);

        boolean hasMessage =
                actual.getProblems().stream().anyMatch(p -> p.getMessage().contains(problemMessage));

        if (!hasMessage) {
            String actualMessages = actual.getProblems().stream()
                    .map(ModelProblem::getMessage)
                    .map(m -> "\"" + m + "\"")

     */
    PersistedToolchains getEffectiveToolchains();

    /**
     * Return a list of problems, if any.
     *
     * @return a list of problems, never {@code null}.
     */
    List<Problem> getProblems();

                }

                @Nonnull
                @Override
                public Collection<BuilderProblem> getProblems() {
                    return new MappedCollection<>(res.getProblems(), this::toProblem);
                }

                private BuilderProblem toProblem(ModelProblem problem) {
                    return new BuilderProblem() {

    public Model getModel() {
        return model;
    }

    @Override
    public ModelBuildingRequest getRequest() {
        return request;
    }

    @Override
    public ModelProblemCollector getProblems() {
        return problems;
    }

     *
     * @return The container used to collect problems that were encountered, never {@code null}.
     */
    ModelProblemCollector getProblems();

    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