@Override
    public <KOut, VOut> KStream<KOut, VOut> process(
        final ProcessorSupplier<? super K, ? super V, KOut, VOut> processorSupplier,
        final String... stateStoreNames
    ) {
        return process(
            processorSupplier,
            Named.as(builder.newProcessorName(PROCESSOR_NAME)),
            stateStoreNames
        );
    }
Repartition a stream. This is required on join operations occurring after
an operation that changes the key, i.e, selectKey, map(..), flatMap(..).
streams/src/main/java/org/apache/kafka/streams/kstream/internals/KStreamImpl.java