code: public List<SubscriptionDescription> getSubscriptions(String topicName) throws ServiceBusException, InterruptedException {
          return Utils.completeFuture(this.asyncClient.getSubscriptionsAsync(topicName));
      }
docs: Retrieves the list of subscriptions for a given topic in the namespace.
  @param topicName - The name of the topic.
  @return the first 100 subscriptions.
  @throws TimeoutException - The operation times out. The timeout period is initiated through ClientSettings.operationTimeout
  @throws AuthorizationFailedException - No sufficient permission to perform this operation. Please check ClientSettings.tokenProvider has correct details.
  @throws ServerBusyException - The server is busy. You should wait before you retry the operation.
  @throws ServiceBusException - An internal error or an unexpected exception occurred.
  @throws InterruptedException if the current thread was interrupted