code: public CompletableFuture<SubscriptionDescription> createSubscriptionAsync(String topicPath, String subscriptionName) {
          return this.createSubscriptionAsync(new SubscriptionDescription(topicPath, subscriptionName));
      }
docs: Creates a new subscription for a given topic in the service namespace with the given name.
  See {@link SubscriptionDescription} for default values of subscription properties.
  @param topicPath - The name of the topic relative to the service namespace base address.
  @param subscriptionName - The name of the subscription.
  @return {@link SubscriptionDescription} of the newly created subscription.
  @throws IllegalArgumentException - Entity name is null, empty, too long or uses illegal characters.