code: public List<Group> getAllGroups(AccessToken accessToken, String... attributes) {
          return getGroupService().getAllGroups(accessToken);
      }
docs: Retrieve a list of the of all {@link Group} resources saved in the OSIAM service. If you need to have all Group
  but the number is very large, this method can be slow. In this case you can also use Query.Builder with no filter
  to split the number of Groups returned
  
  @param accessToken the OSIAM access token for the current session
  @param attributes  the list of attributes that should be returned in the response
  @return a list of all groups
  @throws UnauthorizedException             if the request could not be authorized.
  @throws ForbiddenException                if the scope doesn't allow this request
  @throws ConnectionInitializationException if the connection to the given OSIAM service could not be initialized
  @throws IllegalStateException             if OSIAM's endpoint(s) are not properly configured