@Nullable
    @Override
    public ObjectNode getJsonConfig() {
        final ObjectNode node = super.getJsonConfig();
        JsonUtils.setBoolean(node, CONFIG_KEY_USE_CURRENT_POS, useCurrentPosition);
        JsonUtils.setText(node, CONFIG_KEY_COORD, coordinate == null ? null : GeopointFormatter.format(GeopointFormatter.Format.LAT_LON_DECMINUTE, coordinate));
        return node;
    }
Returns the coordinate which will effectively be used for calculation (either fixed-value or current position)
main/src/main/java/cgeo/geocaching/filters/core/DistanceGeocacheFilter.java