code: public Observable<DeletedCertificateBundle> getDeletedCertificateAsync(String vaultBaseUrl, String certificateName) {
          return getDeletedCertificateWithServiceResponseAsync(vaultBaseUrl, certificateName).map(new Func1<ServiceResponse<DeletedCertificateBundle>, DeletedCertificateBundle>() {
              @Override
              public DeletedCertificateBundle call(ServiceResponse<DeletedCertificateBundle> response) {
                  return response.body();
              }
          });
      }
docs: Retrieves information about the specified deleted certificate.
  The GetDeletedCertificate operation retrieves the deleted certificate information plus its attributes, such as retention interval, scheduled permanent deletion and the current deletion recovery level. This operation requires the certificates/get permission.
  
  @param vaultBaseUrl The vault name, for example https://myvault.vault.azure.net.
  @param certificateName The name of the certificate
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the DeletedCertificateBundle object