@Override
    public void processAllStarts() {
        while ((this.maxBarrierSize == Integer.MAX_VALUE || this.barrier.size() < this.maxBarrierSize) && this.starts.hasNext()) {
            final Traverser.Admin<S> traverser = this.starts.next();
            traverser.setStepId(this.getNextStep().getId()); // when barrier is reloaded, the traversers should be at the next step
            this.barrier.add(traverser);
        }
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/map/NoOpBarrierStep.java