code: // Licensed to the Software Freedom Conservancy (SFC) under one
  // or more contributor license agreements.  See the NOTICE file
  // distributed with this work for additional information
  // regarding copyright ownership.  The SFC licenses this file
  // to you under the Apache License, Version 2.0 (the
  // "License"); you may not use this file except in compliance
  // with the License.  You may obtain a copy of the License at
  //
  //   http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing,
  // software distributed under the License is distributed on an
  // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  // KIND, either express or implied.  See the License for the
  // specific language governing permissions and limitations
  // under the License.
  
  package org.openqa.selenium.testing.drivers;
  
  import java.net.MalformedURLException;
  import java.net.URL;
  import java.util.function.Supplier;
  import org.openqa.selenium.Capabilities;
  import org.openqa.selenium.WebDriver;
  import org.openqa.selenium.remote.Augmenter;
  import org.openqa.selenium.remote.LocalFileDetector;
  import org.openqa.selenium.remote.RemoteWebDriver;
  
  class RemoteSupplier implements Supplier<WebDriver> {
  
    private static OutOfProcessSeleniumServer server = new OutOfProcessSeleniumServer();
    private static volatile boolean started;
    private Capabilities desiredCapabilities;
  
    public RemoteSupplier(Capabilities desiredCapabilities) {
      this.desiredCapabilities = desiredCapabilities;
    }
  
    @Override
    public WebDriver get() {
      if (desiredCapabilities == null || !Boolean.getBoolean("selenium.browser.remote")) {
        return null;
      }
  
      String externalServer = System.getProperty("selenium.externalServer");
      URL serverUrl;
      if (externalServer != null) {
        try {
          serverUrl = new URL(externalServer);
        } catch (MalformedURLException e) {
          throw new RuntimeException(e);
        }
      } else {
        if (!started) {
          startServer();
        }
        serverUrl = server.getWebDriverUrl();
      }
  
      RemoteWebDriver driver = new RemoteWebDriver(serverUrl, desiredCapabilities);
      driver.setFileDetector(new LocalFileDetector());
      return new Augmenter().augment(driver);
    }
  
    private synchronized void startServer() {
      if (started) {
        return;
      }
      server.start("standalone", "--selenium-manager", "true");
      started = true;
    }
  }
  