public Builder vertices(final Traversal<Vertex, ?> vertexPredicate) {
            this.vertexCriterion = vertexPredicate;
            return this;
        }
The traversal predicate that defines the vertices to include in the subgraph. If
{@link #checkAdjacentVertices(boolean)} is {@code true} then this predicate will also be applied to the
adjacent vertices of edges. Take care when setting this value for OLAP based traversals as the traversal
predicate cannot be written in such a way as to leave the local star graph and can thus only evaluate the
current vertex and its related edges.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/strategy/decoration/SubgraphStrategy.java