where can I get the source code for eclipse-plugin of collaborator?

Hello,

Unfortunately, there is no way to get the source code(not an open source). If you want to change something in Collaborator, you can register your request with details here so that our R&D team could consider implementing the feature in the future: http://community.smartbear.com/t5/Collaborator-Feature-Requests/idb-p/CollaboratorFeatureRequests