Blocker Description
Using Gremlin-Java, when the option step modulator is used in combination with a merge step, an `UnsupportedOperationException` is thrown upon calling `next()` if the specified element does not already exist.
Using an example from the docs, the following construct works fine in the console if the element does not already exist:
gremlin> g.mergeV([(T.id):300]). option(Merge.onCreate,[(T.label):'Dog', name:'Toby', age:10]). option(Merge.onMatch,[age:11])
But, if we try to do the same thing in Java, we'll get an exception:
g.mergeV(Map.of(T.id, 300))
.option(
Merge.onCreate,
Map.of(
T.label, "Dog",
"name", "Toby",
"age", 10
)
)
.option(
Merge.onMatch,
Map.of("age", 11)
)
.next();
Exception:
Exception in thread "main" java.lang.UnsupportedOperationException at java.base/java.util.ImmutableCollections.uoe(ImmutableCollections.java:142) at java.base/java.util.ImmutableCollections$AbstractImmutableMap.putAll(ImmutableCollections.java:1073) at org.apache.tinkerpop.gremlin.process.traversal.step.map.MergeVertexStep.onCreateMap(MergeVertexStep.java:205) at org.apache.tinkerpop.gremlin.process.traversal.step.map.MergeVertexStep.flatMap(MergeVertexStep.java:168) at org.apache.tinkerpop.gremlin.process.traversal.step.map.FlatMapStep.processNextStart(FlatMapStep.java:49) at org.apache.tinkerpop.gremlin.process.traversal.step.map.MergeStep.processNextStart(MergeStep.java:165) at org.apache.tinkerpop.gremlin.process.traversal.step.util.AbstractStep.next(AbstractStep.java:135) at org.apache.tinkerpop.gremlin.process.traversal.step.util.AbstractStep.next(AbstractStep.java:40) at org.apache.tinkerpop.gremlin.process.traversal.util.DefaultTraversal.next(DefaultTraversal.java:249) at io.integralla.tinkerpop.poc.MergeWithOption.main(MergeWithOption.java:44)
If the element is first added (via an add or merge step), the merge with option works as expected.
A full example is provided in the attached MergeTestApp.java