@Override
    public boolean equals(Object other) {
        if (this==other) return true;
        if ( ! (other instanceof StringValue)) return false;
        return ((StringValue)other).value.equals(this.value);
    }
Returns the XXHash hashcode of this, to enable strings to be encoded (with reasonable safely)
as doubles for optimization.
searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/StringValue.java