@Override
    protected void onDeserialize(Deserializer buf) {
        super.onDeserialize(buf);
        path = buf.getInt(null);
        globalId = new GlobalId(buf.getBytes(null, GlobalId.LENGTH));
        distributionKey = buf.getInt(null);
        if (distributionKey < 0)
            log.log(Level.WARNING, "Distribution key is negative: " + this);
    }
Returns the distribution key for the node producing this hit.
searchlib/src/main/java/com/yahoo/searchlib/aggregation/FS4Hit.java