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 java.util.Objects;
  import org.openqa.selenium.internal.Require;
  
  public class ContainerId {
  
    private final String id;
  
    public ContainerId(String id) {
      this.id = Require.nonNull("Container id", id);
    }
  
    @Override
    public String toString() {
      return id;
    }
  
    @Override
    public boolean equals(Object o) {
      if (!(o instanceof ContainerId)) {
        return false;
      }
      ContainerId that = (ContainerId) o;
      return Objects.equals(this.id, that.id);
    }
  
    @Override
    public int hashCode() {
      return Objects.hash(id);
    }
  
    private String toJson() {
      return id;
    }
  
    private static ContainerId fromJson(String raw) {
      return new ContainerId(raw);
    }
  }
  