public void append(final byte[] alreadyEncoded, final int offset, final int length) throws java.io.IOException {
        if (shouldCopy(length)) {
            makeRoom(length);
            current.put(alreadyEncoded, offset, length);
        } else {
            append(ByteBuffer.wrap(alreadyEncoded, offset, length));
        }
    }
Data store for AbstractByteWriter. Tested in unit tests for ByteWriter.

@author Steinar Knutsen
vespajlib/src/main/java/com/yahoo/io/BufferChain.java