code: public Observable<CallbackConfigInner> getCallbackConfigAsync(String resourceGroupName, String registryName, String webhookName) {
          return getCallbackConfigWithServiceResponseAsync(resourceGroupName, registryName, webhookName).map(new Func1<ServiceResponse<CallbackConfigInner>, CallbackConfigInner>() {
              @Override
              public CallbackConfigInner call(ServiceResponse<CallbackConfigInner> response) {
                  return response.body();
              }
          });
      }
docs: Gets the configuration of service URI and custom headers for the webhook.
  
  @param resourceGroupName The name of the resource group to which the container registry belongs.
  @param registryName The name of the container registry.
  @param webhookName The name of the webhook.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the CallbackConfigInner object