docs: public Observable<Page<BackupEngineBaseResourceInner>> getAsync(final String vaultName, final String resourceGroupName, final String filter, final String skipToken) {
          return getWithServiceResponseAsync(vaultName, resourceGroupName, filter, skipToken)
              .map(new Func1<ServiceResponse<Page<BackupEngineBaseResourceInner>>, Page<BackupEngineBaseResourceInner>>() {
                  @Override
                  public Page<BackupEngineBaseResourceInner> call(ServiceResponse<Page<BackupEngineBaseResourceInner>> response) {
                      return response.body();
                  }
              });
      }