code: public void start(VersionsSelectionConfiguration configuration) throws AppEngineException {
      Preconditions.checkNotNull(configuration);
      Preconditions.checkNotNull(configuration.getVersions());
      Preconditions.checkArgument(configuration.getVersions().size() > 0);
  
      List<String> arguments = new ArrayList<>();
      arguments.add("app");
      arguments.add("versions");
      arguments.add("start");
      arguments.addAll(commonVersionSelectionArgs(configuration));
  
      execute(arguments);
    }
docs: Starts serving a specific version or versions.
  
  @throws CloudSdkNotFoundException when the Cloud SDK is not installed where expected
  @throws CloudSdkOutOfDateException when the installed Cloud SDK is too old