code: public AppInner createOrUpdate(String resourceGroupName, String resourceName, AppInner app) {
          return createOrUpdateWithServiceResponseAsync(resourceGroupName, resourceName, app).toBlocking().last().body();
      }
docs: Create or update the metadata of an IoT Central application. The usual pattern to modify a property is to retrieve the IoT Central application metadata and security metadata, and then combine them with the modified values in a new body to update the IoT Central application.
  
  @param resourceGroupName The name of the resource group that contains the IoT Central application.
  @param resourceName The ARM resource name of the IoT Central application.
  @param app The IoT Central application metadata and security metadata.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @throws ErrorDetailsException thrown if the request is rejected by server
  @throws RuntimeException all other wrapped checked exceptions if the request fails to be sent
  @return the AppInner object if successful.