@Override
    protected Traverser.Admin<Boolean> processNextStart() throws NoSuchElementException {
        return this.starts.hasNext() ?
                this.starts.next().split(Boolean.TRUE, this) :
                this.getTraversal().getTraverserGenerator().generate(Boolean.FALSE, (Step) this, 1L);
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/map/HasNextStep.java