streams/src/main/java/org/apache/kafka/streams/kstream/internals/SlidingWindowedKStreamImpl.java [145:186]:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
                materializedInternal.valueSerde());
    }

    @Override
    public KTable<Windowed<K>, V> reduce(final Reducer<V> reducer) {
        return reduce(reducer, NamedInternal.empty());
    }

    @Override
    public KTable<Windowed<K>, V> reduce(final Reducer<V> reducer, final Named named) {
        return reduce(reducer, named, Materialized.with(keySerde, valueSerde));
    }

    @Override
    public KTable<Windowed<K>, V> reduce(final Reducer<V> reducer,
                                         final Materialized<K, V, WindowStore<Bytes, byte[]>> materialized) {
        return reduce(reducer, NamedInternal.empty(), materialized);
    }

    @Override
    public KTable<Windowed<K>, V> reduce(final Reducer<V> reducer,
                                         final Named named,
                                         final Materialized<K, V, WindowStore<Bytes, byte[]>> materialized) {
        Objects.requireNonNull(reducer, "reducer can't be null");
        Objects.requireNonNull(named, "named can't be null");
        Objects.requireNonNull(materialized, "materialized can't be null");

        final MaterializedInternal<K, V, WindowStore<Bytes, byte[]>> materializedInternal =
                new MaterializedInternal<>(materialized, builder, REDUCE_NAME);

        if (materializedInternal.keySerde() == null) {
            materializedInternal.withKeySerde(keySerde);
        }
        if (materializedInternal.valueSerde() == null) {
            materializedInternal.withValueSerde(valueSerde);
        }

        final String reduceName = new NamedInternal(named).orElseGenerateWithPrefix(builder, REDUCE_NAME);

        return aggregateBuilder.build(
                new NamedInternal(reduceName),
                materialize(materializedInternal),
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -



streams/src/main/java/org/apache/kafka/streams/kstream/internals/TimeWindowedKStreamImpl.java [162:205]:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
                materializedInternal.valueSerde());


    }

    @Override
    public KTable<Windowed<K>, V> reduce(final Reducer<V> reducer) {
        return reduce(reducer, NamedInternal.empty());
    }

    @Override
    public KTable<Windowed<K>, V> reduce(final Reducer<V> reducer, final Named named) {
        return reduce(reducer, named, Materialized.with(keySerde, valueSerde));
    }

    @Override
    public KTable<Windowed<K>, V> reduce(final Reducer<V> reducer,
                                         final Materialized<K, V, WindowStore<Bytes, byte[]>> materialized) {
        return reduce(reducer, NamedInternal.empty(), materialized);
    }

    @Override
    public KTable<Windowed<K>, V> reduce(final Reducer<V> reducer,
                                         final Named named,
                                         final Materialized<K, V, WindowStore<Bytes, byte[]>> materialized) {
        Objects.requireNonNull(reducer, "reducer can't be null");
        Objects.requireNonNull(named, "named can't be null");
        Objects.requireNonNull(materialized, "materialized can't be null");

        final MaterializedInternal<K, V, WindowStore<Bytes, byte[]>> materializedInternal =
            new MaterializedInternal<>(materialized, builder, REDUCE_NAME);

        if (materializedInternal.keySerde() == null) {
            materializedInternal.withKeySerde(keySerde);
        }
        if (materializedInternal.valueSerde() == null) {
            materializedInternal.withValueSerde(valueSerde);
        }

        final String reduceName = new NamedInternal(named).orElseGenerateWithPrefix(builder, REDUCE_NAME);

        return aggregateBuilder.build(
                new NamedInternal(reduceName),
                materialize(materializedInternal),
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -