code: @Override
      public GetCertificateAuthorityCsrResult getCertificateAuthorityCsr(GetCertificateAuthorityCsrRequest request) {
          request = beforeClientExecution(request);
          return executeGetCertificateAuthorityCsr(request);
      }
docs: <p>
  Retrieves the certificate signing request (CSR) for your private certificate authority (CA). The CSR is created
  when you call the <a>CreateCertificateAuthority</a> operation. Take the CSR to your on-premises X.509
  infrastructure and sign it by using your root or a subordinate CA. Then import the signed certificate back into
  ACM PCA by calling the <a>ImportCertificateAuthorityCertificate</a> operation. The CSR is returned as a base64
  PEM-encoded string.
  </p>
  
  @param getCertificateAuthorityCsrRequest
  @return Result of the GetCertificateAuthorityCsr operation returned by the service.
  @throws RequestInProgressException
  Your request is already in progress.
  @throws RequestFailedException
  The request has failed for an unspecified reason.
  @throws ResourceNotFoundException
  A resource such as a private CA, S3 bucket, certificate, or audit report cannot be found.
  @throws InvalidArnException
  The requested Amazon Resource Name (ARN) does not refer to an existing resource.
  @throws InvalidStateException
  The private CA is in a state during which a report or certificate cannot be generated.
  @sample AWSACMPCA.GetCertificateAuthorityCsr
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/acm-pca-2017-08-22/GetCertificateAuthorityCsr"
  target="_top">AWS API Documentation</a>