Order

The spark-shell show may show an "ambiguous reference to overloaded definition" error for two functions: GraphTraversal.by(Order) and GraphTraversal.by(Comparable)

Here is an example:

scala>  g.V().values("name").order().by(Order.decr)
console>:43: error: ambiguous reference to overloaded definition,
both method by in trait GraphTraversal of type (x$1: org.apache.tinkerpop.gremlin.process.traversal.Order)org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal[org.apache.spark.sql.Row,E2]
and  method by in trait GraphTraversal of type (x$1: java.util.Comparator[E2])org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal[org.apache.spark.sql.Row,E2]
match argument types (org.apache.tinkerpop.gremlin.process.traversal.Order)

To workaround this problem a user can directly cast Order to super class: Comparable

scala> g.V().values("name").order().by(Order.decr.asInstanceOf[Order])

This is an inconvenient workaround, so this class replicates the Order interface but returns Comparable instead of Order. Users should import this object to avoid the aforementioned issues.