code: public Observable<Page<ProtectableContainerResourceInner>> listAsync(final String vaultName, final String resourceGroupName, final String fabricName, final String filter) {
          return listWithServiceResponseAsync(vaultName, resourceGroupName, fabricName, filter)
              .map(new Func1<ServiceResponse<Page<ProtectableContainerResourceInner>>, Page<ProtectableContainerResourceInner>>() {
                  @Override
                  public Page<ProtectableContainerResourceInner> call(ServiceResponse<Page<ProtectableContainerResourceInner>> response) {
                      return response.body();
                  }
              });
      }
docs: Lists the containers registered to Recovery Services Vault.
  
  @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 with the container.
  @param filter OData filter options.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the PagedList&lt;ProtectableContainerResourceInner&gt; object