Github user kinow commented on the issue:
https://github.com/apache/jena/pull/114
Rebase'd against master. Added `TestJsonEval.java`, with a couple more
tests. Then understood why the projected variables were not working.
Updated the grammar to call the method that populates the `projectedVars`
collection. Now queries like `JSON { 'F' : 'string' } WHERE { }` resolve to `[
{ 'F' : 'string' } ]`.
Still need to work around the other comment about `Double`s.---
