code: public LuisApp export(UUID appId, String versionId) {
          return exportWithServiceResponseAsync(appId, versionId).toBlocking().single().body();
      }
docs: Exports a LUIS application to JSON format.
  
  @param appId The application ID.
  @param versionId The version ID.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @throws ErrorResponseException thrown if the request is rejected by server
  @throws RuntimeException all other wrapped checked exceptions if the request fails to be sent
  @return the LuisApp object if successful.