@Override
    public int hashCode() {
        return Objects.hash(super.hashCode(), alternatives);
    }
Add a new alternative iff the term string is not already present with an
equal or higher exactness score. If the term string is present with a
lower exactness score, the new, higher score will take precedence.

@param term one of several string interpretations of the input word
@param exactness how close the term string matches what the user input
container-search/src/main/java/com/yahoo/prelude/query/WordAlternativesItem.java