code: public Observable<Page<FileServerInner>> listByResourceGroupNextAsync(final String nextPageLink) {
          return listByResourceGroupNextWithServiceResponseAsync(nextPageLink)
              .map(new Func1<ServiceResponse<Page<FileServerInner>>, Page<FileServerInner>>() {
                  @Override
                  public Page<FileServerInner> call(ServiceResponse<Page<FileServerInner>> response) {
                      return response.body();
                  }
              });
      }
docs: Gets a list of File Servers within the specified resource group.
  
  @param nextPageLink The NextLink from the previous successful call to List operation.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the PagedList&lt;FileServerInner&gt; object