return new MappedCollection<>(res.getProblems(), this::toProblem);
                }

                private BuilderProblem toProblem(ModelProblem problem) {
                    return new BuilderProblem() {
                        @Override
                        public String getSource() {
                            return problem.getSource();
                        }

                        @Override

                        (problemsCount == 1) ? "problem was" : "problems were",
                        result.getProjectId());

                if (request.isShowErrors()) { // this means -e or -X (as -X enables -e as well)
                    for (ModelProblem problem : result.getProblems()) {
                        String loc = ModelProblemUtils.formatLocation(problem, result.getProjectId());

Here's what to keep in mind and how to review a pull request:

### Understand the problem { #understand-the-problem }

* First, make sure you **understand the problem** that the pull request is trying to solve. It might have a longer discussion in a GitHub Discussion or issue.

* There's also a good chance that the pull request is not actually needed because the problem can be solved in a **different way**. Then you can suggest or ask about that.

### Das Problem verstehen { #understand-the-problem }

* Stellen Sie zunächst sicher, dass Sie **das Problem verstehen**, welches der Pull Request zu lösen versucht. Möglicherweise gibt es eine längere Diskussion dazu in einer GitHub-Diskussion oder einem GitHub-Issue.

     */
    @Nonnull
    List<Profile> getActiveExternalProfiles();

    /**
     * Gets the problem collector that collected problems encountered during the project building.
     *
     * @return the problem collector that collected problems encountered during the project building
     */
    @Nonnull
    ProblemCollector<ModelProblem> getProblemCollector();

    /**

          <offlineLinks>
            <!-- We need local copies of some of these for 2 reasons: a User-Agent problem (https://stackoverflow.com/a/47891403/28465) and an SSL problem (https://issues.apache.org/jira/browse/MJAVADOC-507). If we choose to work around the User-Agent problem, we can go back to <links>, sidestepping the SSL problem. -->
            <offlineLink>

     * and child directory == artifactId
     * @throws IOException Model read problem
     */
    @Test
    void testUrls() throws Exception {
        testInheritance("urls");
    }

    /**
     * Flat directory structure: parent & child POMs in sibling directories, child directory == artifactId.
     * @throws IOException Model read problem
     */
    @Test
    void testFlatUrls() throws IOException {

          <offlineLinks>
            <!-- We need local copies of some of these for 2 reasons: a User-Agent problem (https://stackoverflow.com/a/47891403/28465) and an SSL problem (https://issues.apache.org/jira/browse/MJAVADOC-507). If we choose to work around the User-Agent problem, we can go back to <links>, sidestepping the SSL problem. -->
            <offlineLink>

   * A word about using {@link Equivalence}, which automatically checks for {@code null} and
   * identical inputs: This sounds like it ought to be a problem here, since the goals of this class
   * include testing that {@code equals()} is reflexive and is tolerant of {@code null}. However,
   * there's no problem. The reason: {@link EqualsTester} tests {@code null} and identical inputs
   * directly against {@code equals()} rather than through the {@code Equivalence}.

   * nullness analysis might not understand that the field has been populated. To avoid that problem
   * without having to add {@code @SuppressWarnings}, the code can call this method.
   *
   * <p>Why <i>not</i> just add {@code SuppressWarnings}? The problem is that this method is
   * typically useful for {@code return} statements. That leaves the code with two options: Either