code: public BoxRequestsShare.AddCollaboration getAddRequest(BoxCollaborationItem collaborationItem, BoxCollaboration.Role role, String login) {
          BoxRequestsShare.AddCollaboration collab = new BoxRequestsShare.AddCollaboration(getCollaborationsUrl(),
                  createStubItem(collaborationItem), role, login, mSession);
          return collab;
      }
docs: A request that adds a user as a collaborator to an item by using their login.
  @param collaborationItem item to be collaborated.
  @param role role of the collaboration
  @param login email address of the user to add
  @return request to add/create a collaboration