chore: Revert "feat(sns): addSubscription returns the created Subscri…

…ption (aws#16785)" (aws#17166)

This reverts commit 62f389e.

Changing the return type from void to Subscription is a breaking change for F# customers, where the return type changes from "unit" to "Subscription", potentially breaking `do` statements.

Example:
https://github.com/aws/aws-cdk/blob/62f389ea0522cbaefca5ca17080228031d401ce6/packages/aws-cdk/lib/init-templates/v1/sample-app/fsharp/src/%25name.PascalCased%25/%25name.PascalCased%25Stack.template.fs#L14

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/@aws-cdk/aws-sns/lib/topic-base.ts

@@ -31,7 +31,7 @@ export interface ITopic extends IResource, notifications.INotificationRuleTarget
   /**
    * Subscribe some endpoint to this topic
    */
-  addSubscription(subscription: ITopicSubscription): Subscription;
+  addSubscription(subscription: ITopicSubscription): void;
 
   /**
    * Adds a statement to the IAM resource policy associated with this topic.
@@ -68,7 +68,7 @@ export abstract class TopicBase extends Resource implements ITopic {
   /**
    * Subscribe some endpoint to this topic
    */
-  public addSubscription(subscription: ITopicSubscription): Subscription {
+  public addSubscription(subscription: ITopicSubscription) {
     const subscriptionConfig = subscription.bind(this);
 
     const scope = subscriptionConfig.subscriberScope || this;
@@ -83,7 +83,7 @@ export abstract class TopicBase extends Resource implements ITopic {
       throw new Error(`A subscription with id "${id}" already exists under the scope ${scope.node.path}`);
     }
 
-    return new Subscription(scope, id, {
+    new Subscription(scope, id, {
       topic: this,
       ...subscriptionConfig,
     });

packages/@aws-cdk/aws-sns/test/sns.test.ts

@@ -480,26 +480,4 @@ describe('Topic', () => {
 
 
   });
-
-  test('result of addSubscription() can be used as a dependency', () => {
-    // GIVEN
-    const stack = new cdk.Stack();
-    const topic = new sns.Topic(stack, 'Topic');
-    const user = new iam.User(stack, 'User');
-
-    // WHEN
-    const subscription = topic.addSubscription({
-      bind: () => ({
-        protocol: sns.SubscriptionProtocol.HTTP,
-        endpoint: 'http://foo/bar',
-        subscriberId: 'my-subscription',
-      }),
-    });
-    user.node.addDependency(subscription);
-
-    // THEN
-    Template.fromStack(stack).hasResource('AWS::IAM::User', {
-      DependsOn: ['Topicmysubscription1E605DD7'],
-    });
-  });
 });