private BufferValue getBuffered(final Bytes key) {
        final BufferKey bufferKey = index.get(key);
        return bufferKey == null ? null : sortedMap.get(bufferKey);
    }
As of 2.1, there's no way for users to directly interact with the buffer,
so this method is implemented solely to be called by Streams (which
it will do based on the {@code cache.max.bytes.buffering} config.
<p>
It's currently a no-op.
streams/src/main/java/org/apache/kafka/streams/state/internals/InMemoryTimeOrderedKeyValueChangeBuffer.java