ResourceId resourceId = new ResourceId();
resourceId.setChannelId(channelId);
resourceId.setKind("youtube#channel");
// Create a snippet that contains the resourceId.
SubscriptionSnippet snippet = new SubscriptionSnippet();
snippet.setResourceId(resourceId);
// Create a request to add the subscription and send the request.
// The request identifies subscription metadata to insert as well
// as information that the API server should return in its response.
Subscription subscription = new Subscription();