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.support.locators;
  
  import static org.openqa.selenium.support.locators.RelativeLocatorScript.FIND_ELEMENTS;
  
  import com.google.auto.service.AutoService;
  import com.google.common.collect.ImmutableMap;
  import java.util.List;
  import org.openqa.selenium.By;
  import org.openqa.selenium.InvalidArgumentException;
  import org.openqa.selenium.JavascriptExecutor;
  import org.openqa.selenium.SearchContext;
  import org.openqa.selenium.WebDriver;
  import org.openqa.selenium.WebElement;
  import org.openqa.selenium.internal.Require;
  import org.openqa.selenium.remote.JsonToWebElementConverter;
  import org.openqa.selenium.remote.RemoteWebDriver;
  import org.openqa.selenium.remote.locators.CustomLocator;
  
  @AutoService(CustomLocator.class)
  public class RelativeLocatorServerSide implements CustomLocator {
    @Override
    public String getLocatorName() {
      return "relative";
    }
  
    @Override
    public By createBy(Object usingParameter) {
      Require.nonNull("Using", usingParameter);
      return new RemoteRelative(usingParameter);
    }
  
    private static class RemoteRelative extends By {
      private final Object using;
  
      private RemoteRelative(Object usingParameter) {
        using = usingParameter;
      }
  
      @Override
      public List<WebElement> findElements(SearchContext context) {
        JavascriptExecutor js = getJavascriptExecutor(context);
  
        WebDriver driver = getWebDriver(context);
  
        if (driver instanceof RemoteWebDriver) {
          Object converted = new JsonToWebElementConverter((RemoteWebDriver) driver).apply(using);
  
          @SuppressWarnings("unchecked")
          List<WebElement> elements =
              (List<WebElement>)
                  js.executeScript(FIND_ELEMENTS, ImmutableMap.of("relative", converted));
          return elements;
        }
  
        throw new InvalidArgumentException("Unable to find element");
      }
    }
  }
  