This hot fix can be downloaded from the SFDC Customer Portal Web UI, using your username and password for support.tibco.com.  Once logged on you can find the hotfix under Download Menu :

AvailableDownloads/BusinessWorks/Plugins/REST_JSON/2.1.0/hotfix-09

Listed below is a summary of updates included. Please refer to the associated read me document for any additional information.

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Closed Issues in 2.1.0_HF-009 (This Release)

Defect ID: REST-1702

    Validation error with Header and Query parameters in "Invoke Rest API" when using Swagger.
    
Enhancement ID: REST-1732

    Product level fix for the property Empty2Null in design-time for RenderJSON activity. 
    
    If your project is designed with REST-JSON 2.1.0 HF-08 or lesser and configured with "java.property.com.tibco.plugin.restjson.xml2json.empty2null" and is deployed then no change in behaviour(like your previous version). If project is opened in designer with REST-JSON 2.1.0 HF-09 then the design time changes will be reflected with the checkbox - "Use Null for Empty values".
    By default the checkbox is checked. 
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