code: public Observable<Page<SharedAccessSignatureAuthorizationRuleInner>> listKeysNextAsync(final String nextPageLink) {
          return listKeysNextWithServiceResponseAsync(nextPageLink)
              .map(new Func1<ServiceResponse<Page<SharedAccessSignatureAuthorizationRuleInner>>, Page<SharedAccessSignatureAuthorizationRuleInner>>() {
                  @Override
                  public Page<SharedAccessSignatureAuthorizationRuleInner> call(ServiceResponse<Page<SharedAccessSignatureAuthorizationRuleInner>> response) {
                      return response.body();
                  }
              });
      }
docs: Get the security metadata for an IoT hub. For more information, see: https://docs.microsoft.com/azure/iot-hub/iot-hub-devguide-security.
  Get the security metadata for an IoT hub. For more information, see: https://docs.microsoft.com/azure/iot-hub/iot-hub-devguide-security.
  
  @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;SharedAccessSignatureAuthorizationRuleInner&gt; object