@Override
        public Set<StoreBuilder<?>> stores() {
            return Collections.singleton(Stores.keyValueStoreBuilder(
                Stores.inMemoryKeyValueStore("Counts"),
                Serdes.String(),
                Serdes.Integer()));
        }
Demonstrates, using a {@link Processor} implementing the low-level Processor APIs (replaces Transformer),
how to implement the WordCount program that computes a simple word occurrence histogram from an input text.
<p>
<strong>Note: This is simplified code that only works correctly for single partition input topics.
Check out {@link WordCountDemo} for a generic example.</strong>
<p>
In this example, the input stream reads from a topic named "streams-plaintext-input", where the values of messages
represent lines of text; and the histogram output is written to topic "streams-wordcount-processor-output" where each record
is an updated count of a single word.
<p>
This example differs from {@link WordCountProcessorDemo} in that it uses a {@link ProcessorSupplier} to attach the Processor with the
count logic to the Stream, and the topology is wired up through a {@link StreamsBuilder},
which more closely resembles the high-level DSL (compared to the Topology builder approach, with Source, Processor, Sink).
<p>
Before running this example you must create the input topic and the output topic (e.g. via
{@code bin/kafka-topics.sh --create ...}), and write some data to the input topic (e.g. via
{@code bin/kafka-console-producer.sh}). Otherwise you won't see any data arriving in the output topic.
streams/examples/src/main/java/org/apache/kafka/streams/examples/wordcount/WordCountTransformerDemo.java