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.docker;
  
  import static org.openqa.selenium.json.Json.MAP_TYPE;
  import static org.openqa.selenium.remote.http.HttpMethod.GET;
  
  import com.google.common.collect.ImmutableMap;
  import java.io.UncheckedIOException;
  import java.util.Map;
  import java.util.Optional;
  import java.util.function.Function;
  import org.openqa.selenium.docker.v1_41.V141Docker;
  import org.openqa.selenium.internal.Require;
  import org.openqa.selenium.json.Json;
  import org.openqa.selenium.json.JsonException;
  import org.openqa.selenium.remote.http.Contents;
  import org.openqa.selenium.remote.http.HttpHandler;
  import org.openqa.selenium.remote.http.HttpRequest;
  import org.openqa.selenium.remote.http.HttpResponse;
  
  class VersionCommand {
  
    private static final Json JSON = new Json();
    // Insertion order matters, and is preserved by ImmutableMap.
    private static final Map<Version, Function<HttpHandler, DockerProtocol>> SUPPORTED_VERSIONS =
        ImmutableMap.of(new Version("1.40"), V141Docker::new);
  
    private final HttpHandler handler;
  
    public VersionCommand(HttpHandler handler) {
      this.handler = Require.nonNull("HTTP client", handler);
    }
  
    public Optional<DockerProtocol> getDockerProtocol() {
      try {
        HttpResponse res = handler.execute(new HttpRequest(GET, "/version"));
  
        if (!res.isSuccessful()) {
          return Optional.empty();
        }
  
        Map<String, Object> raw = JSON.toType(Contents.string(res), MAP_TYPE);
  
        Version maxVersion = new Version((String) raw.get("ApiVersion"));
        Version minVersion = new Version((String) raw.get("MinAPIVersion"));
  
        return SUPPORTED_VERSIONS.entrySet().stream()
            .filter(
                entry -> {
                  Version version = entry.getKey();
                  if (version.equalTo(maxVersion) || version.equalTo(minVersion)) {
                    return true;
                  }
                  return version.isLessThan(maxVersion) && version.isGreaterThan(minVersion);
                })
            .map(Map.Entry::getValue)
            .map(func -> func.apply(handler))
            .findFirst();
      } catch (ClassCastException | JsonException | NullPointerException | UncheckedIOException e) {
        return Optional.empty();
      }
    }
  }
  