@Override public Set<String> vertexMatchPatternLabels(){
  return labels.size() == 1 ? labels : Collections.emptySet();
}

@ Override public Set < String > vertexMatchPatternLabels ( ) { return labels . size ( ) == 1 ? labels : Collections . emptySet ( ) ; }
gets the set of labels required at the time of matching the vertex in a cypher match pattern . this implementation returns a single label if partition contains a single label , otherwise an empty set ( predicate required to match vertices ) .
