public static void setSortConfig(final String sortContextKey, final String sortConfig) {
        if (sortConfig == null) {
            removeDirect(getKey(R.string.pref_cache_sort_config) + "." + sortContextKey);
        } else {
            putStringDirect(getKey(R.string.pref_cache_sort_config) + "." + sortContextKey, sortConfig);
        }
    }
Should SOLELY be called by class {@link cgeo.geocaching.sorting.GeocacheSortContext}!
main/src/main/java/cgeo/geocaching/settings/Settings.java