.filter(p -> !request.getPluginGroups().contains(p.getGroupId()))
                .collect(Collectors.groupingBy(
                        Plugin::getGroupId,
                        LinkedHashMap::new,
                        Collectors.mapping(Plugin::getArtifactId, Collectors.toSet())));
        request.getPluginGroups().forEach(g -> candidates.put(g, null));

                    dominantActiveProfiles.add(profileId);
                }
            }
        }

        List<String> dominantPluginGroupIds = dominant.getPluginGroups();

        List<String> recessivePluginGroupIds = recessive.getPluginGroups();

        if (recessivePluginGroupIds != null) {
            if (dominantPluginGroupIds == null) {
                dominantPluginGroupIds = new ArrayList<>();

        }

        setPluginGroups(session.getPluginGroups());
    }

    @Override
    public String getPrefix() {
        return prefix;
    }

    @Override
    public DefaultPluginPrefixRequest setPrefix(String prefix) {
        this.prefix = prefix;

        return this;
    }

    @Override
    public List<String> getPluginGroups() {
        return pluginGroups;
    }

    @Override

        }

        return this;
    }

    @Override
    public MavenExecutionRequest addPluginGroup(String pluginGroup) {
        if (!getPluginGroups().contains(pluginGroup)) {
            getPluginGroups().add(pluginGroup);
        }

        return this;
    }

    @Override
    public MavenExecutionRequest addPluginGroups(List<String> pluginGroups) {

    /**
     * Gets the list of group ids to scan for the plugin prefix.
     *
     * @return The list of group ids to scan for the plugin prefix, never {@code null}.
     */
    List<String> getPluginGroups();

    /**
     * Sets the list of group ids to scan for the plugin prefix.
     *
     * @param pluginGroups The list of group ids to scan for the plugin prefix, may be {@code null}.

    public ProjectBuildingRequest getProjectBuildingRequest() {
        return request.getProjectBuildingRequest().setRepositorySession(getRepositorySession());
    }

    public List<String> getPluginGroups() {
        return request.getPluginGroups();
    }

    public boolean isOffline() {
        return request.isOffline();
    }

    public MavenProject getTopLevelProject() {
        return topLevelProject;
    }

                .pluginGroups(Arrays.asList("org.codehaus.plexus"))
                .build();

        Settings merged = SettingsUtilsV4.merge(dominant, recessive);

        List<String> pluginGroups = merged.getPluginGroups();

        assertNotNull(pluginGroups);
        assertEquals(3, pluginGroups.size());
        assertEquals("org.apache.maven.plugins", pluginGroups.get(0));

            return request;
        }

        request.setOffline(settings.isOffline());

        request.setInteractiveMode(settings.isInteractiveMode());

        request.setPluginGroups(settings.getPluginGroups());

        request.setLocalRepositoryPath(settings.getLocalRepository());

        for (Server server : settings.getServers()) {
            request.addServer(server);
        }

            return request;
        }

        request.setOffline(settings.isOffline());

        request.setInteractiveMode(settings.isInteractiveMode());

        request.setPluginGroups(settings.getPluginGroups());

        request.setLocalRepositoryPath(settings.getLocalRepository());

        for (Server server : settings.getServers()) {
            server = server.clone();

        if (settings.isUsePluginRegistry()) {
            addViolation(problems, Severity.WARNING, "usePluginRegistry", null, "is deprecated and has no effect.");
        }

        List<String> pluginGroups = settings.getPluginGroups();

        if (pluginGroups != null) {
            for (int i = 0; i < pluginGroups.size(); i++) {
                String pluginGroup = pluginGroups.get(i).trim();

                if (pluginGroup.isEmpty()) {