code: public void authenticateConnection (Invoker invoker, final AuthingConnection conn,
                                          final ResultListener<AuthingConnection> onComplete)
      {
          final AuthRequest req = conn.getAuthRequest();
          final AuthResponseData rdata = createResponseData();
          final AuthResponse rsp = new AuthResponse(rdata);
  
          invoker.postUnit(new Invoker.Unit("authenticateConnection") {
              @Override
              public boolean invoke () {
                  try {
                      processAuthentication(conn, rsp);
                      if (AuthResponseData.SUCCESS.equals(rdata.code) &&
                          conn.getAuthName() == null) { // fail early, fail (less) often
                          throw new IllegalStateException("Authenticator failed to provide authname");
                      }
                  } catch (AuthException e) {
                      rdata.code = e.getMessage();
                  } catch (Exception e) {
                      log.warning("Error authenticating user", "areq", req, e);
                      rdata.code = AuthCodes.SERVER_ERROR;
                  }
                  return true;
              }
  
              @Override
              public void handleResult () {
                  // stuff a reference to the auth response into the connection so that we have
                  // access to it later in the authentication process
                  conn.setAuthResponse(rsp);
  
                  // send the response back to the client
                  conn.postMessage(rsp);
  
                  // if the authentication request was granted, let the connection manager know that
                  // we just authed
                  if (AuthResponseData.SUCCESS.equals(rdata.code)) {
                      onComplete.requestCompleted(conn);
                  }
              }
          });
      }
docs: Called by the connection management code when an authenticating connection has received its
  authentication request from the client.