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.grid.config;
  
  import static org.openqa.selenium.json.Json.MAP_TYPE;
  
  import java.io.IOException;
  import java.io.Reader;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.util.List;
  import java.util.Optional;
  import java.util.Set;
  import org.openqa.selenium.internal.Require;
  import org.openqa.selenium.json.Json;
  import org.openqa.selenium.json.JsonException;
  
  public class JsonConfig implements Config {
  
    private static final Json JSON = new Json();
    private final Config delegate;
  
    JsonConfig(Reader reader) {
      try {
        delegate = new MapConfig(JSON.toType(Require.nonNull("JSON source", reader), MAP_TYPE));
      } catch (JsonException e) {
        throw new ConfigException("Unable to parse input", e);
      }
    }
  
    public static Config from(Path path) {
      try (Reader reader = Files.newBufferedReader(path)) {
        return new JsonConfig(reader);
      } catch (IOException e) {
        throw new ConfigException("Unable to read JSON.", e);
      }
    }
  
    @Override
    public Optional<List<String>> getAll(String section, String option) {
      return delegate.getAll(section, option);
    }
  
    @Override
    public Set<String> getSectionNames() {
      return delegate.getSectionNames();
    }
  
    @Override
    public Set<String> getOptions(String section) {
      return delegate.getOptions(Require.nonNull("Section name to get options for", section));
    }
  }
  