public default BulkSet<E> toBulkSet() {
        return this.fill(new BulkSet<>());
    }
Put all the results into a {@link BulkSet}.
This can reduce both time and space when aggregating results by ensuring a weighted set.

@return the results in a bulk set
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/Traversal.java