Gremlin 3.5.4 gives error from Java code but not from gremlin console (Connecting to Neptune)

[gauravsingh96]

Hi team, I have followed the following link https://docs.aws.amazon.com/neptune/latest/userguide/access-graph-gremlin-java.html to create a sample application. This works fine. But when I add one traversal to add a vertex it fails saying the {"requestId":"xyz","code":"ConstraintViolationException","detailedMessage":"Vertex with id already exists: "} even though the id is not ingested. The traversal that I have added is -

g.inject(1).union(__.addV('label').property(T.id, 'uniqueId1').property('prop1','val1')).valueMap(true)

What is surprising the same query runs from the gremlin console and does not complain about vertex already ingested.

Is there something in the query that must be changed for it to run from the code ?