MAXSTRING error on conversion to JSON in FHIR R4 DTL

I'm working on FHIR project and using this code to convert an incoming request to FHIR 

Method OnRequest(request As HS.FHIRServer.Interop.Request, Output response As HS.FHIRServer.Interop.Response) As %Status

{

    #dim tSC As %Status = $$$OK

    Try {

        // Process incoming request

       

        set stream = ##class(HS.SDA3.QuickStream).%OpenId(request.QuickStreamId)

        set bundle = ##class(HS.FHIR.DTL.vR4.Model.Resource.Bundle).FromJSON(stream,"vR4")

 

It's working ok but when I include a realistic PDF in a FHIR Binary resource (contained in the Bundle) I get a MAXSTRING error. 

Looking at the documentation for HS.FHIR.DTL.vR4.Model.Resource.Binary, I wondering if MAXLEN setting for data is missing and data MAXLEN = 50. 
 

Property contentType As %String(MAXLEN = 1000000, XMLNAME = "contentType", XMLPROJECTION = "ATTRIBUTE") [ Required ];

Property data As %Binary(XMLNAME = "data", XMLPROJECTION = "ATTRIBUTE");