code: func (s *UserService) GetGroups(username string) (*[]UserGroup, *Response, error) {
  	apiEndpoint := fmt.Sprintf("/rest/api/2/user/groups?username=%s", username)
  	req, err := s.client.NewRequest("GET", apiEndpoint, nil)
  	if err != nil {
  		return nil, nil, err
  	}
  
  	userGroups := new([]UserGroup)
  	resp, err := s.client.Do(req, userGroups)
  	if err != nil {
  		return nil, resp, NewJiraError(resp, err)
  	}
  	return userGroups, resp, nil
  }
docs: // GetGroups returns the groups which the user belongs to
  //
  // JIRA API docs: https://docs.atlassian.com/jira/REST/cloud/#api/2/user-getUserGroups