PomTestWrapper pom = buildPom("build-extension-inheritance/sub");
        assertEquals(3, ((List<?>) pom.getValue("build/extensions")).size());
        assertEquals("b", pom.getValue("build/extensions[1]/artifactId"));
        assertEquals("a", pom.getValue("build/extensions[2]/artifactId"));
        assertEquals("0.2", pom.getValue("build/extensions[2]/version"));

     *
     * @param classRealm The class realm hosting the build extensions of this project, may be {@code null}.
     */
    public void setClassRealm(ClassRealm classRealm) {
        this.classRealm = classRealm;
    }

    /**
     * Gets the project's class realm. This class realm hosts the build extensions of the project.

            // extensionArtifacts
            Set<Artifact> extensionArtifacts = new HashSet<>();
            List<Extension> extensions =
                    project.getModel().getDelegate().getBuild().getExtensions();
            if (extensions != null) {
                for (Extension ext : extensions) {
                    String version;
                    if (ext.getVersion() == null || ext.getVersion().isEmpty()) {

        if (excludeExtensions == null) {
            excludeExtensions = split(getThumbnailHtmlImageExcludeExtensions(), ",").get(stream -> stream
                    .map(s -> s.toLowerCase(Locale.ROOT).trim()).filter(StringUtil::isNotBlank).toArray(n -> new String[n]));
            propMap.put(THUMBNAIL_HTML_IMAGE_EXCLUDE_EXTENSIONS, excludeExtensions);
        }

                            p.getInherited(),
                            p.getKey(),
                            p);

                    validateBoolean(
                            "build.plugins.plugin.extensions",
                            EMPTY,
                            problems,
                            errOn30,
                            Version.V20,
                            p.getExtensions(),

 * Kotlin code. In this class, nothing is publicly visible (nor exposed indirectly through a
 * publicly visible subclass), and I doubt any of our current or future Kotlin extensions for the
 * package will refer to the class. Plus, @ParametricNullness is only a temporary workaround,
 * anyway, so we just need to get by without the annotations here until Kotlin better understands