code: private Vertex initNewVertex(GDLParser.VertexContext vertexContext) {
      Vertex v = new Vertex();
      v.setId(getNewVertexId());
      List<String> labels = getLabels(vertexContext.header());
      v.setLabels(labels.isEmpty() ?
        useDefaultVertexLabel ? Collections.singletonList(defaultVertexLabel) : Collections.emptyList()
        : labels);
      v.setProperties(getProperties(vertexContext.properties()));
  
      return v;
    }
docs: Initializes a new vertex from a given vertex context.
  
  @param vertexContext vertex context
  @return new vertex