Suggestion widget in Studio should work with Elasticsearch page providers

I want to use a ES page provider in a suggestion widget.

In the current implementation I've seen with Benjamin that a malformed query is generated.

Steps:

1. contribute a test page provider (NXQL_PP_PATTERN from the nuxeo-elasticsearch-core unit tests is a good one)
2. set up a generic suggestion widget and set the page provider as the Document page provider name

See attached server.log for ArrayIndexOutOfBoundsException. A copy of my Studio project is also attached.