@Override
        public String toString() {
            return "ValueStatValue{" +
                    "value=" + value +
                    ", count=" + count +
                    '}';
        }
Adds entries from another aggregate map into this one.

@param aggregateMap
stroom-statistics/stroom-statistics-impl-sql/src/main/java/stroom/statistics/impl/sql/SQLStatisticAggregateMap.java