ユーザーのアバターを取得

curl -i -X GET "https://api.box.com/2.0/users/12345/avatar" \
     -H "authorization: Bearer <ACCESS_TOKEN>"

Stream imageStream = await client.UsersManager.GetUserAvatar(string userId);

String userID = "33333";
// some stream do download avatar
try (ByteArrayOutputStream outputStream = new ByteArrayOutputStream()){
  BoxUser user=new BoxUser(api,userID);
  user.downloadAvatar(outputStream);
} catch (IOException e) {
  throw new RuntimeException(e);
}

avatar = client.user('33333').get_avatar()

client.users.getAvatar('22222')
    .then(avatarImageStream => {

        avatarImageStream.on('data', bytes => {
            // read avatar image bytes
        });
    });

client.users.getAvatar(userId: "33333") { (result: Result<Data, BoxSDKError>) in
    guard case let .success(avatarData) = result else {
        print("Error getting user avatar")
        return
    }

    let avatarImage = UIImage(data: avatarData)
}