/**
     * Gets the user settings source.
     *
     * @return the user settings source or {@code null} if none
     */
    @Nonnull
    Optional<Source> getUserSettingsSource();

    /**
     * The optional interpolation source used for interpolation.
     *
     * @return the interpolation source for interpolation
     */
    @Nonnull

        LOGGER.debug(
                "Reading user settings from '{}'",
                getLocation(settingsRequest.getUserSettingsSource(), settingsRequest.getUserSettingsFile()));

        SettingsBuildingResult settingsResult = settingsBuilder.build(settingsRequest);

        if (request.getEventSpyDispatcher() != null) {

        Settings globalSettings = readSettings(globalSettingsSource, request, problems);

        Source userSettingsSource = getSettingsSource(request.getUserSettingsFile(), request.getUserSettingsSource());
        Settings userSettings = readSettings(userSettingsSource, request, problems);

        settingsMerger.merge(userSettings, globalSettings, TrackableBase.GLOBAL_LEVEL);

        problems.setSource("");