@Override
        public byte[] get(final Bytes key) {
            final byte[] bufferValue = data.get(key);
            if (bufferValue != null) {
                return bufferValue;
            }
            return dbSegment.get(key);
        }
The object representation of the write buffer corresponding to a single segment store.
Contains the write buffer itself (a simple hash map) and also a reference to the underlying
persistent segment store.
streams/src/main/java/org/apache/kafka/streams/state/internals/RocksDBVersionedStoreRestoreWriteBuffer.java