code: public Observable<Void> refreshAsync(String vaultName, String resourceGroupName, String fabricName, String filter) {
          return refreshWithServiceResponseAsync(vaultName, resourceGroupName, fabricName, filter).map(new Func1<ServiceResponse<Void>, Void>() {
              @Override
              public Void call(ServiceResponse<Void> response) {
                  return response.body();
              }
          });
      }
docs: Discovers all the containers in the subscription that can be backed up to Recovery Services Vault. This is an asynchronous operation. To know the status of the operation, call GetRefreshOperationResult API.
  
  @param vaultName The name of the recovery services vault.
  @param resourceGroupName The name of the resource group where the recovery services vault is present.
  @param fabricName Fabric name associated the container.
  @param filter OData filter options.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the {@link ServiceResponse} object if successful.