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-04

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

================================================================================
Closed Issues in 2.1.0_HF-004 (This Release)

Defect ID: REST-1546

    Invoke REST API threw an error when requestURI had space. 

Defect ID: REST-1532

    After installing HF3, Invoke REST API returned blank JSON string as response 
    body.

Defect ID: REST-1525

    Invkoe REST API was not able to parse unicode to characters for the 
    response JSON data.

Defect ID: REST-1489

    For REST plugin 2.1.0, when using Invoke REST API, received following warning 
    message "NoClassDefFoundError: org/jvnet/mimepull/MIMEParsingException".
================================================================================