func (s *ActivityService) ListStarred(ctx context.Context, user string, opt *ActivityListStarredOptions) ([]*StarredRepository, *Response, error) {
	var u string
	if user != "" {
		u = fmt.Sprintf("users/%v/starred", user)
	} else {
		u = "user/starred"
	}
	u, err := addOptions(u, opt)
	if err != nil {
		return nil, nil, err
	}
	req, err := s.client.NewRequest("GET", u, nil)
	if err != nil {
		return nil, nil, err
	}
	acceptHeaders := []string{mediaTypeStarringPreview, mediaTypeTopicsPreview}
	req.Header.Set("Accept", strings.Join(acceptHeaders, ", "))
	var repos []*StarredRepository
	resp, err := s.client.Do(ctx, req, &repos)
	if err != nil {
		return nil, resp, err
	}
	return repos, resp, nil
}
ListStarred lists all the repos starred by a user. Passing the empty string
will list the starred repositories for the authenticated user.

GitHub API docs: https://developer.github.com/v3/activity/starring/#list-repositories-being-starred
package github
import (
	"context"
	"fmt"
	"strings"
)
type StarredRepository struct {
	StarredAt  *Timestamp  `json:"starred_at,omitempty"`
	Repository *Repository `json:"repo,omitempty"`
}
type Stargazer struct {
	StarredAt *Timestamp `json:"starred_at,omitempty"`
	User      *User      `json:"user,omitempty"`
}
func (s *ActivityService) ListStargazers(ctx context.Context, owner, repo string, opt *ListOptions) ([]*Stargazer, *Response, error) {
	u := fmt.Sprintf("repos/%s/%s/stargazers", owner, repo)
	u, err := addOptions(u, opt)
	if err != nil {
		return nil, nil, err
	}
	req, err := s.client.NewRequest("GET", u, nil)
	if err != nil {
		return nil, nil, err
	}
	req.Header.Set("Accept", mediaTypeStarringPreview)
	var stargazers []*Stargazer
	resp, err := s.client.Do(ctx, req, &stargazers)
	if err != nil {
		return nil, resp, err
	}
	return stargazers, resp, nil
}
type ActivityListStarredOptions struct {
	Sort string `url:"sort,omitempty"`
	Direction string `url:"direction,omitempty"`
	ListOptions
}