code: public CertificateInner createOrUpdate(String resourceGroupName, String name, CertificateInner certificateEnvelope) {
          return createOrUpdateWithServiceResponseAsync(resourceGroupName, name, certificateEnvelope).toBlocking().single().body();
      }
docs: Create or update a certificate.
  Create or update a certificate.
  
  @param resourceGroupName Name of the resource group to which the resource belongs.
  @param name Name of the certificate.
  @param certificateEnvelope Details of certificate, if it exists already.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @throws CloudException thrown if the request is rejected by server
  @throws RuntimeException all other wrapped checked exceptions if the request fails to be sent
  @return the CertificateInner object if successful.