https://groups.google.com/g/google-appengine/c/8SwY1gxjLdM
Bulk Uploader with ReferenceProperty
bulk uploader
https://tinkerpop.apache.org/javadocs/3.7.6-SNAPSHOT/full/org/apache/tinkerpop/gremlin/structure/util/reference/ReferenceProperty.html
ReferenceProperty (Apache TinkerPop 3.7.6-SNAPSHOT API)
apache tinkerpopsnapshotapi