private static final String ISSUES_KEY = DefaultPluginValidationManager.class.getName() + ".issues";

    private static final String PLUGIN_EXCLUDES_KEY = DefaultPluginValidationManager.class.getName() + ".excludes";

    private static final String MAVEN_PLUGIN_VALIDATION_KEY = "maven.plugin.validation";

    private static final String MAVEN_PLUGIN_VALIDATION_EXCLUDES_KEY = "maven.plugin.validation.excludes";

     * same class realm is used to load build extensions and load mojos for extensions=true plugins.
     * </p>
     * <strong>Note:</strong> This is part of internal implementation and may be changed or removed without notice
     *
     * @since 3.3.0
     */

    private static final SessionData.Key<ProjectIndex> PROJECT_INDEX = SessionData.key(ProjectIndex.class);

    @SuppressWarnings({"unchecked", "rawtypes"})
    private static final SessionData.Key<Map<MavenProject, OwnerReentrantLock>> PROJECT_LOCKS =
            (SessionData.Key) SessionData.key(Map.class, ProjectLock.class);

    private final BuildPluginManager pluginManager;

        String key = "m2.name";
        String checkValue = "value";

        MavenProject project = createDefaultProject();
        project.getModel().getProperties().setProperty(key, checkValue);

        ExpressionEvaluator ee = createExpressionEvaluator(project, new Properties());

        Object value = ee.evaluate("${" + key + "}");

        assertEquals(checkValue, value);
    }

        Map<String, List<ArtifactRepository>> reposByKey = new LinkedHashMap<>();

        for (ArtifactRepository repository : repositories) {
            String key = repository.getId();

            List<ArtifactRepository> aliasedRepos = reposByKey.computeIfAbsent(key, k -> new ArrayList<>());

            aliasedRepos.add(repository);
        }

        List<ArtifactRepository> effectiveRepositories = new ArrayList<>();

     * This map is usually either empty if no module was found, or a singleton map.
     * It may however contain more than one entry if module hierarchy was detected,
     * in which case there is one key per sub-directory.
     *
     * <p>This map may contain null values if the constructor was invoked with {@code resolve}
     * parameter set to false. This is more efficient when only the module existence needs to

        String var = "${var}";
        String key = var + " with version: ${project.version}";

        Model model = new Model();
        model.setVersion("1");

        MavenProject project = new MavenProject(model);

        ExpressionEvaluator ee = createExpressionEvaluator(project, null, new Properties());

        Object value = ee.evaluate("$" + key);

        assertEquals("${var} with version: 1", value);

                throws ArtifactMetadataRetrievalException {
            String key = getKey(artifact);

            ArtifactSpec a = (ArtifactSpec) artifacts.get(key);
            try {
                return new ResolutionGroup(
                        artifact,
                        createArtifacts(

                try {
                    return Optional.of(injector.getInstance(Key.of(type, name)));
                } catch (DIException e) {
                    return Optional.empty();
                }
            }

            @Override
            public <T> List<T> lookupList(Class<T> type) {
                return injector.getInstance(new Key<List<T>>() {});
            }

            @Override

        fireEvent(ResolutionListener.TEST_ARTIFACT, listeners, node);

        Object key = node.getKey();

        // TODO Does this check need to happen here? Had to add the same call
        // below when we iterate on child nodes -- will that suffice?
        if (managedVersions.containsKey(key)) {
            manageArtifact(node, managedVersions, listeners);
        }