Two forums exist:

OpenCDS Users

The users forum is the place to ask technical questions, share ideas and insights, and discuss the future directions for OpenCDS.  You are encouraged to discuss or ask questions about the following (or anything else related to OpenCDS):

• Demo Server Configuration
• Authoring Environment (Guvnor) Configuration
• Development Environment (Eclipse) Configuration
• Creating and maintaining Knowledge Modules for OpenCDS
• Using HL7 virtual Medical Records (vMR) for OpenCDS
• Using HL7 Consolidated Clinical Document Architecture (CCDA) with OpenCDS
• Usiing HL7 Fast Healthcare Interoperability Resources (FHIR) with OpenCDS

Link: https://groups.google.com/forum/#!forum/opencds-users

OpenCDS Developers

The users group is intended for technical discussions and questions about the internal construction of OpenCDS.  
It is intended to be used by persons who are maintaining, extending, or otherwise working with the OpenCDS source code.  
Appropriate discussions for this forum would include topics such as:

• efforts to produce new inferencing adapters for new versions of Drools or other inferencing engines such as WEKA,
• creation or use of alternative or updated internal data models, such as CIMI,
• extension mechanisms which add functionality or alternative interfaces,
• directly embedding OpenCDS in client software, such as an EHR,
• building infrastructure components for OpenCDS such as Smart on FHIR and CDS Hooks
• etc.

Link: https://groups.google.com/forum/#!forum/opencds-dev