code: public void updateBuildpackInstallations(String appName, List<String> buildpacks) {
          connection.execute(new BuildpackInstallationUpdate(appName, buildpacks), apiKey);
      }
docs: Update the list of buildpacks installed on an app
  
  @param appName See {@link #listApps} for a list of apps that can be used.
  @param buildpacks the new list of buildpack names or URLs.