code: public Observable<CertificateBundle> mergeCertificateAsync(String vaultBaseUrl, String certificateName, List<byte[]> x509Certificates) {
          return mergeCertificateWithServiceResponseAsync(vaultBaseUrl, certificateName, x509Certificates).map(new Func1<ServiceResponse<CertificateBundle>, CertificateBundle>() {
              @Override
              public CertificateBundle call(ServiceResponse<CertificateBundle> response) {
                  return response.body();
              }
          });
      }
docs: Merges a certificate or a certificate chain with a key pair existing on the server.
  The MergeCertificate operation performs the merging of a certificate or certificate chain with a key pair currently available in the service. This operation requires the certificates/create permission.
  
  @param vaultBaseUrl The vault name, for example https://myvault.vault.azure.net.
  @param certificateName The name of the certificate.
  @param x509Certificates The certificate or the certificate chain to merge.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the CertificateBundle object