@Override
    public synchronized void putAll(final List<KeyValue<K, V>> entries) {
        for (final KeyValue<K, V> entry : entries) {
            put(entry.key, entry.value);
        }
    }
This class is a generic version of the in-memory key-value store that is useful for testing when you
 need a basic KeyValueStore for arbitrary types and don't have/want to write a serde
streams/src/test/java/org/apache/kafka/test/GenericInMemoryKeyValueStore.java