code: public Observable<Page<SecretItem>> getSecretsNextAsync(final String nextPageLink) {
          return getSecretsNextWithServiceResponseAsync(nextPageLink)
              .map(new Func1<ServiceResponse<Page<SecretItem>>, Page<SecretItem>>() {
                  @Override
                  public Page<SecretItem> call(ServiceResponse<Page<SecretItem>> response) {
                      return response.body();
                  }
              });
      }
docs: List secrets in a specified key vault.
  The Get Secrets operation is applicable to the entire vault. However, only the base secret identifier and its attributes are provided in the response. Individual secret versions are not listed in the response. This operation requires the secrets/list permission.
  
  @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;SecretItem&gt; object