Exception when using multiple return values

I am not sure whether this is already possible.

I'm specifying ASTs and am creating CPGs from them. I had some trouble finding out how return values need to be specified. I think that there needs to be a gap of 1 between the last order of an input parameter (METHOD_PARAMETER_IN) and the order of the (first) return value (METHOD_RETURN). This seems to work reliably as long as there only is 1 return value.

Are multiple return values already possible?

Both if I increment order further for a second return value and if I leave it just the same as ther first return value's order, I get this error message:

[error] (Writer) java.lang.RuntimeException: Edge of type CFG with direction OUT not supported by class MethodReturnDb
[error] java.lang.RuntimeException: Edge of type CFG with direction OUT not supported by class MethodReturnDb
[error]         at overflowdb.NodeDb.storeAdjacentNode(NodeDb.java:621)
[error]         at overflowdb.NodeDb.storeAdjacentNode(NodeDb.java:602)
[error]         at overflowdb.NodeDb.addEdge(NodeDb.java:298)
[error]         at overflowdb.NodeRef.addEdge(NodeRef.java:151)
[error]         at overflowdb.SemiEdge.$minus$minus$greater(SyntacticSugar.scala:59)
[error]         at io.shiftleft.passes.DiffGraph$Applier.odbAddEdge(DiffGraph.scala:388)
[error]         at io.shiftleft.passes.DiffGraph$Applier.addEdge(DiffGraph.scala:380)
[error]         at io.shiftleft.passes.DiffGraph$Applier.$anonfun$run$1(DiffGraph.scala:332)
[error]         at io.shiftleft.passes.DiffGraph$Applier.$anonfun$run$1$adapted(DiffGraph.scala:328)
[error]         at scala.collection.IterableOnceOps.foreach(IterableOnce.scala:576)
[error]         at scala.collection.IterableOnceOps.foreach$(IterableOnce.scala:574)
[error]         at scala.collection.AbstractIterator.foreach(Iterator.scala:1196)
[error]         at io.shiftleft.passes.DiffGraph$Applier.run(DiffGraph.scala:328)
[error]         at io.shiftleft.passes.DiffGraph$Applier$.applyDiff(DiffGraph.scala:417)
[error]         at io.shiftleft.passes.ParallelCpgPass$Writer.run(ParallelCpgPass.scala:105)
[error]         at java.lang.Thread.run(Thread.java:748)

It is thrown only when building the CPG, not when just specifying the AST.

Reproduce the failure by specifying an AST with multiple METHOD_RETURN nodes and building a CPG, rather than only specifying the AST. Start with MethodReturnDb and the DiffGraph.Applier.addEdge path shown in the stack trace; done means CPG construction accepts multiple return values without the CFG edge exception.