code: @Override
      public ConfirmSubscriptionResult confirmSubscription(ConfirmSubscriptionRequest request) {
          request = beforeClientExecution(request);
          return executeConfirmSubscription(request);
      }
docs: <p>
  Verifies an endpoint owner's intent to receive messages by validating the token sent to the endpoint by an
  earlier <code>Subscribe</code> action. If the token is valid, the action creates a new subscription and returns
  its Amazon Resource Name (ARN). This call requires an AWS signature only when the
  <code>AuthenticateOnUnsubscribe</code> flag is set to "true".
  </p>
  
  @param confirmSubscriptionRequest
  Input for ConfirmSubscription action.
  @return Result of the ConfirmSubscription operation returned by the service.
  @throws SubscriptionLimitExceededException
  Indicates that the customer already owns the maximum allowed number of subscriptions.
  @throws InvalidParameterException
  Indicates that a request parameter does not comply with the associated constraints.
  @throws NotFoundException
  Indicates that the requested resource does not exist.
  @throws InternalErrorException
  Indicates an internal service error.
  @throws AuthorizationErrorException
  Indicates that the user has been denied access to the requested resource.
  @throws FilterPolicyLimitExceededException
  Indicates that the number of filter polices in your AWS account exceeds the limit. To add more filter
  polices, submit an SNS Limit Increase case in the AWS Support Center.
  @sample AmazonSNS.ConfirmSubscription
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/sns-2010-03-31/ConfirmSubscription" target="_top">AWS API
  Documentation</a>