code: public static <Key, Value> Aggregation<Key, Value, Long> count() {
          return new AggregationAdapter(new CountAggregation<Key, Value>());
      }
docs: Returns an aggregation for counting all supplied values.<br/>
  This aggregation is similar to: <pre>SELECT COUNT(*) FROM x</pre>
  
  @param <Key> the input key type
  @param <Value> the supplied value type
  @return the count of all supplied elements