@Override
    public <VAgg> KTable<K, VAgg> aggregate(final Initializer<VAgg> initializer,
                                      final Aggregator<? super K, ? super V, VAgg> adder,
                                      final Aggregator<? super K, ? super V, VAgg> subtractor) {
        return aggregate(initializer, adder, subtractor, Materialized.with(keySerde, null));
    }
The implementation class of {@link KGroupedTable}.

@param <K> the key type
@param <V> the value type
streams/src/main/java/org/apache/kafka/streams/kstream/internals/KGroupedTableImpl.java