code: public ServiceFuture<List<SasDefinitionItem>> getSasDefinitionsAsync(final String vaultBaseUrl, final String storageAccountName, final Integer maxresults, final ListOperationCallback<SasDefinitionItem> serviceCallback) {
          return AzureServiceFuture.fromPageResponse(
              getSasDefinitionsSinglePageAsync(vaultBaseUrl, storageAccountName, maxresults),
              new Func1<String, Observable<ServiceResponse<Page<SasDefinitionItem>>>>() {
                  @Override
                  public Observable<ServiceResponse<Page<SasDefinitionItem>>> call(String nextPageLink) {
                      return getSasDefinitionsNextSinglePageAsync(nextPageLink);
                  }
              },
              serviceCallback);
      }
docs: List storage SAS definitions for the given storage account. This operation requires the storage/listsas permission.
  
  @param vaultBaseUrl The vault name, for example https://myvault.vault.azure.net.
  @param storageAccountName The name of the storage account.
  @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