code: public Observable<List<CertificateEmailInner>> retrieveCertificateEmailHistoryAsync(String resourceGroupName, String name) {
          return retrieveCertificateEmailHistoryWithServiceResponseAsync(resourceGroupName, name).map(new Func1<ServiceResponse<List<CertificateEmailInner>>, List<CertificateEmailInner>>() {
              @Override
              public List<CertificateEmailInner> call(ServiceResponse<List<CertificateEmailInner>> response) {
                  return response.body();
              }
          });
      }
docs: Retrieve email history.
  Retrieve email history.
  
  @param resourceGroupName Name of the resource group to which the resource belongs.
  @param name Name of the certificate order.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the List&lt;CertificateEmailInner&gt; object