code: public IssuerBundle getCertificateIssuer(String vaultBaseUrl, String issuerName) {
          return getCertificateIssuerWithServiceResponseAsync(vaultBaseUrl, issuerName).toBlocking().single().body();
      }
docs: Lists the specified certificate issuer.
  The GetCertificateIssuer operation returns the specified certificate issuer resources in the specified key vault. This operation requires the certificates/manageissuers/getissuers permission.
  
  @param vaultBaseUrl The vault name, for example https://myvault.vault.azure.net.
  @param issuerName The name of the issuer.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @throws KeyVaultErrorException thrown if the request is rejected by server
  @throws RuntimeException all other wrapped checked exceptions if the request fails to be sent
  @return the IssuerBundle object if successful.