code: @Override
      public RegisterCertificateResult registerCertificate(RegisterCertificateRequest request) {
          request = beforeClientExecution(request);
          return executeRegisterCertificate(request);
      }
docs: <p>
  Registers a device certificate with AWS IoT. If you have more than one CA certificate that has the same subject
  field, you must specify the CA certificate that was used to sign the device certificate being registered.
  </p>
  
  @param registerCertificateRequest
  The input to the RegisterCertificate operation.
  @return Result of the RegisterCertificate operation returned by the service.
  @throws ResourceAlreadyExistsException
  The resource already exists.
  @throws InvalidRequestException
  The request is not valid.
  @throws CertificateValidationException
  The certificate is invalid.
  @throws CertificateStateException
  The certificate operation is not allowed.
  @throws CertificateConflictException
  Unable to verify the CA certificate used to sign the device certificate you are attempting to register.
  This is happens when you have registered more than one CA certificate that has the same subject field and
  public key.
  @throws ThrottlingException
  The rate exceeds the limit.
  @throws UnauthorizedException
  You are not authorized to perform this operation.
  @throws ServiceUnavailableException
  The service is temporarily unavailable.
  @throws InternalFailureException
  An unexpected error has occurred.
  @sample AWSIot.RegisterCertificate