code: func (s *IssueService) GetTransitions(id string) ([]Transition, *Response, error) {
  	apiEndpoint := fmt.Sprintf("rest/api/2/issue/%s/transitions?expand=transitions.fields", id)
  	req, err := s.client.NewRequest("GET", apiEndpoint, nil)
  	if err != nil {
  		return nil, nil, err
  	}
  
  	result := new(transitionResult)
  	resp, err := s.client.Do(req, result)
  	if err != nil {
  		err = NewJiraError(resp, err)
  	}
  	return result.Transitions, resp, err
  }
docs: // GetTransitions gets a list of the transitions possible for this issue by the current user,
  // along with fields that are required and their types.
  //
  // JIRA API docs: https://docs.atlassian.com/jira/REST/latest/#api/2/issue-getTransitions