code: public VertexElement addVertexElementWithEdgeIdProperty(Schema.BaseType baseType, ConceptId conceptId) {
          Objects.requireNonNull(conceptId);
          Vertex vertex = graph.addVertex(baseType.name());
          long start = System.currentTimeMillis();
          vertex.property(Schema.VertexProperty.EDGE_RELATION_ID.name(), conceptId.getValue());
          assignVertexIdPropertyTime += System.currentTimeMillis() - start;
          return new VertexElement(tx, vertex);
      }
docs: Creates a new Vertex in the graph and builds a VertexElement which wraps the newly created vertex
  @param baseType   The Schema.BaseType
  @param conceptId the ConceptId to set as the new ConceptId
  @return a new VertexElement
  
  NB: this is only called when we reify an EdgeRelation - we want to preserve the ID property of the concept