Github user spmallette commented on the issue:
https://github.com/apache/tinkerpop/pull/922
@mattallenuk I figured out what was going on. The `EnumValue` was being
interpreted as a `Map` when serializing to GraphSON. The change is pretty
trivial, but I have a bunch of other little changes here/there. I'm going to
merge this PR to a TINKERPOP-1959 branch for review (hope that's ok with you)
and hopefully we can get this merged up today. ---
