code: public CompletableFuture<RuleDescription> updateRuleAsync(String topicName, String subscriptionName, RuleDescription ruleDescription) {
          return putRuleAsync(topicName, subscriptionName, ruleDescription, true);
      }
docs: Updates an existing rule.
  @param topicName - Name of the topic.
  @param subscriptionName - Name of the subscription.
  @param ruleDescription - A {@link RuleDescription} object describing the attributes with which the rule will be updated.
  @return {@link RuleDescription} of the updated rule.
  @throws IllegalArgumentException - descriptor is null.