@Override
    public boolean equals(Object o) {
        if (o == this) return true;
        if (!(o instanceof Pair)) return false;

        @SuppressWarnings("rawtypes")
        Pair other = (Pair) o;
        return Objects.equals(this.first, other.first) && Objects.equals(this.second, other.second);
    }
Returns the second member. This may be null.
vespajlib/src/main/java/com/yahoo/collections/Pair.java