code: public ServiceFuture<FeatureResultInner> registerAsync(String resourceProviderNamespace, String featureName, final ServiceCallback<FeatureResultInner> serviceCallback) {
          return ServiceFuture.fromResponse(registerWithServiceResponseAsync(resourceProviderNamespace, featureName), serviceCallback);
      }
docs: Registers the preview feature for the subscription.
  
  @param resourceProviderNamespace The namespace of the resource provider.
  @param featureName The name of the feature to register.
  @param serviceCallback the async ServiceCallback to handle successful and failed responses.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the {@link ServiceFuture} object