@Override
    public boolean add(E e) {
        if (e == null) {
            throw new NullPointerException("Buckets do not accept null elements.");
        }

        if (!this.content.add(e)) {
            return false;
        }

        this.partitions.get(this.strategy.allocate(e, this)).add(e);
        return true;
    }
Supplies the set instances to use for each partition in the bucket

@return a new set
helper/src/main/java/me/lucko/helper/bucket/AbstractBucket.java