Hi Laura,

No answer but some relevant search results:

https://groups.google.com/g/gremlin-users/c/jUBuhhKuf0M/m/kiKMY0eHAwAJ
The  graph.set-vertex-id property at: https://docs.janusgraph.org/configs/configuration-reference/#graph

In general, when working with JanusGraph, it is better to first transform the input graphml and make the id into a property.

Best wishes,   Marc