@SuppressWarnings("deprecation") // Old PAPI. Needs to be migrated.
    private <K, V> org.apache.kafka.streams.processor.ProcessorSupplier<K, V> define(final org.apache.kafka.streams.processor.Processor<K, V> processor) {
        return () -> processor;
    }
A processor that stores each key-value pair in an in-memory key-value store registered with the context.
streams/src/test/java/org/apache/kafka/streams/processor/internals/ProcessorTopologyTest.java