public static void fillSearchParameterCenter(@NonNull final Map<String, String> valueMap, @NonNull final Parameters params, @Nullable final Geopoint center, final String radius) {
        final Geopoint usedCenter = center != null ? center : LocationDataProvider.getInstance().currentGeo().getCoords();
        final String centerString = GeopointFormatter.format(GeopointFormatter.Format.LAT_DECDEGREE_RAW, usedCenter) + SEPARATOR + GeopointFormatter.format(GeopointFormatter.Format.LON_DECDEGREE_RAW, usedCenter);
        valueMap.put("center", centerString);
        valueMap.put("radius", radius);
        params.removeKey("search_method");
        params.put("search_method", METHOD_SEARCH_NEAREST);
    }
Client for the OpenCaching API (Okapi).

@see <a href="http://www.opencaching.de/okapi/introduction.html">Okapi overview</a>
main/src/main/java/cgeo/geocaching/connector/oc/OkapiClient.java