A text with SPARQL variable syntax in a string is interpreted as a SPARQL variable

[hhv]

I am not sure if this is the right repository for this. I am trying to load a lot of JSON-LD into Fluree and in one of the chunks that I am uploading I see this:

    "http://linkeddata.overheid.nl/terms/heeftZaaknummer" : {
      "@value" : "?WB 09"
    },
    "rdfs:label" : {
      "@value" : "ECLI:NL:RBUTR:2011:2694 - Rechtbank Utrecht, 06-10-2011 / ?WB 09"
    },
    "http://purl.org/dc/terms/title" : {
      "@value" : "ECLI:NL:RBUTR:2011:2694 - Rechtbank Utrecht, 06-10-2011 / ?WB 09"
    },

This generate an error:

[{:type clojure.lang.ExceptionInfo
fluree-1              |    :message "Parsing failure due to: variable ?WB 09 is not bound in where nor values clause.

Errr... it is very well possible that I do not know enough JSON-LD but this seems odd to me. Is that a correct interpretation of the data by Fluree?