code: @Override
      public GetSigningCertificateResult getSigningCertificate(GetSigningCertificateRequest request) {
          request = beforeClientExecution(request);
          return executeGetSigningCertificate(request);
      }
docs: <p>
  This method takes a user pool ID, and returns the signing certificate.
  </p>
  
  @param getSigningCertificateRequest
  Request to get a signing certificate from Cognito.
  @return Result of the GetSigningCertificate operation returned by the service.
  @throws InternalErrorException
  This exception is thrown when Amazon Cognito encounters an internal error.
  @throws ResourceNotFoundException
  This exception is thrown when the Amazon Cognito service cannot find the requested resource.
  @sample AWSCognitoIdentityProvider.GetSigningCertificate
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/cognito-idp-2016-04-18/GetSigningCertificate"
  target="_top">AWS API Documentation</a>