@Override
    public void write(FieldBase field, Raw value) {
        ByteBuffer rawBuf = value.getByteBuffer();
        int origPos = rawBuf.position();
        buf.putInt(rawBuf.remaining());
        buf.put(rawBuf);
        rawBuf.position(origPos);

    }
Write out the value of raw field

@param field - field description (name and data type)
@param value - field value
document/src/main/java/com/yahoo/document/serialization/VespaDocumentSerializer6.java