@Override
    public void setJsonConfig(@NonNull final ObjectNode config) {
        super.setJsonConfig(config);
        useCurrentPosition = JsonUtils.getBoolean(config, CONFIG_KEY_USE_CURRENT_POS, false);
        final String coordText = JsonUtils.getText(config, CONFIG_KEY_COORD, null);
        coordinate = coordText == null ? null : GeopointParser.parse(coordText, null);
    }
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