@Override
    public void writeString(int fieldNumber, CharSequence value, boolean repeated) throws IOException
    {
        byte[] bytes = STRING.ser(value.toString());

        int tag = WireFormat.makeTag(fieldNumber, WireFormat.WIRETYPE_LENGTH_DELIMITED);
        byte[] delimited = CodedOutput.getTagAndRawVarInt32Bytes(tag, bytes.length);
        size += delimited.length + bytes.length;

        current = new ByteArrayNode(bytes, new ByteArrayNode(delimited, current));
    }
Returns the data written to this output as a single byte array.
protostuff-core/src/test/java/io/protostuff/DeferredOutput.java