docs: public URIBuilder appendFilter(URIBuilder builder, Collection<Filter<?>> filters) {
  		if (filters.size() > 0) {
  			ObjectNode filterNode = new ObjectMapper().createObjectNode();
  			for (Filter<?> filter : filters) {
  				filterNode.setAll(filter.toJson());
  			}
  			ObjectNode drilldownNode = new ObjectMapper().createObjectNode();
  			drilldownNode.put("drilldown", filterNode);
  			builder.addParameter("filter", drilldownNode.toString());
  		}
  		return builder;
  	}