code: public ServiceFuture<List<CertificateIssuerItem>> getCertificateIssuersAsync(final String vaultBaseUrl, final Integer maxresults, final ListOperationCallback<CertificateIssuerItem> serviceCallback) {
          return AzureServiceFuture.fromPageResponse(
              getCertificateIssuersSinglePageAsync(vaultBaseUrl, maxresults),
              new Func1<String, Observable<ServiceResponse<Page<CertificateIssuerItem>>>>() {
                  @Override
                  public Observable<ServiceResponse<Page<CertificateIssuerItem>>> call(String nextPageLink) {
                      return getCertificateIssuersNextSinglePageAsync(nextPageLink);
                  }
              },
              serviceCallback);
      }
docs: List certificate issuers for a specified key vault.
  The GetCertificateIssuers operation returns the set of 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 maxresults Maximum number of results to return in a page. If not specified the service will return up to 25 results.
  @param serviceCallback the async ServiceCallback to handle successful and failed responses.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the {@link ServiceFuture} object