code: public ServiceFuture<List<VaultInner>> listBySubscriptionAsync(final Integer top, final ListOperationCallback<VaultInner> serviceCallback) {
          return AzureServiceFuture.fromPageResponse(
              listBySubscriptionSinglePageAsync(top),
              new Func1<String, Observable<ServiceResponse<Page<VaultInner>>>>() {
                  @Override
                  public Observable<ServiceResponse<Page<VaultInner>>> call(String nextPageLink) {
                      return listBySubscriptionNextSinglePageAsync(nextPageLink);
                  }
              },
              serviceCallback);
      }
docs: The List operation gets information about the vaults associated with the subscription.
  
  @param top Maximum number of results to return.
  @param serviceCallback the async ServiceCallback to handle successful and failed responses.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the {@link ServiceFuture} object