Our application uses angular js as the front end framework and Spring framework in the backend.
The examples given by groupdocs are more of a closed nature . Is there a way we can integrate the viewer and the group docs java annotations with the stack I have mentioned above ?
Out of the box the GroupDocs.Viewer contains the HTML5 front-end build on jQuery. You can check and investigate what requests it performs and implement your own front-end or modify this one to support the Angular JS framework.
You can also review the com.groupdocs.viewer.handlers.ViewerHandler API (with and without HTTP support) and use then in case of need for the Angular JS back-end support.