@Override
    public int hashCode() {
        if (getId() == null) {
            throw new IllegalStateException("This hit must have a 'uri' field, and this field must be filled through " +
                                            "Execution.fill(Result)) before hashCode() is accessed.");
        } else {
            return super.hashCode();
        }
    }
Returns whether any fields are present <b>in the field map in the parent hit</b>
container-search/src/main/java/com/yahoo/prelude/fastsearch/FastHit.java