in src/main/java/com/googlesource/gerrit/plugins/hooks/AgreementSignup.java [34:45]
  public void onAgreementSignup(AgreementSignupListener.Event event) {
    AccountInfo submitter = event.getAccount();
    if (submitter != null) {
      HookArgs args = hookFactory.createArgs();
      args.add("--submitter", submitter);
      args.add("--user-id", submitter._accountId);
      args.add("--cla-name", event.getAgreementName());
      hook.execute(args);
    }
  }