public GraphTraversal<Vertex, Object> convertToVertexPropertyId(final String vertexName, final String vertexPropertyKey) {
        return convertToVertexPropertyId(graph, vertexName, vertexPropertyKey);
    }
Looks up the identifier as generated by the current source graph being tested.

@param graph      the graph to get the element id from
@param vertexName a unique string that will identify a graph element within a graph
@return the id as generated by the graph
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/AbstractGremlinTest.java