public List<BaseGeocacheFilter> getAndChainIfPossible() {
        final List<BaseGeocacheFilter> result = new ArrayList<>();
        getAndChainIfPossibleInternal(this.getTree(), result);
        return result;
    }
Helper method to map filter to search providers only offering AND filter capability.
* If this filter is a base filter, this base filter is returned
* If this is an AND filter, extract the "AND" chain of Base filters.
* Otherwise return an empty list
main/src/main/java/cgeo/geocaching/filters/core/GeocacheFilter.java