public Joined<K, V, VO> withKeySerde(final Serde<K> keySerde) {
        return new Joined<>(keySerde, valueSerde, otherValueSerde, name, gracePeriod);
    }
Set the key {@link Serde} to be used. Null values are accepted and will be replaced by the default
key serde as defined in config

@param keySerde the key serde to use. If null the default key serde from config will be used
@return new {@code Joined} instance configured with the {@code name}
streams/src/main/java/org/apache/kafka/streams/kstream/Joined.java