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.graphql;
  
  import java.time.Instant;
  import java.time.ZoneId;
  import java.time.format.DateTimeFormatter;
  import java.util.UUID;
  import org.openqa.selenium.Capabilities;
  import org.openqa.selenium.ImmutableCapabilities;
  import org.openqa.selenium.internal.Require;
  import org.openqa.selenium.json.Json;
  
  public class Slot {
  
    private static final DateTimeFormatter DATE_TIME_FORMATTER =
        DateTimeFormatter.ofPattern("dd/MM/yyyy HH:mm:ss").withZone(ZoneId.systemDefault());
  
    private final UUID id;
    private final Capabilities stereotype;
    private final Instant lastStarted;
    private static final Json JSON = new Json();
  
    public Slot(UUID id, Capabilities stereotype, Instant lastStarted) {
      this.id = Require.nonNull("Slot ID", id);
      this.stereotype = ImmutableCapabilities.copyOf(Require.nonNull("Stereotype", stereotype));
      this.lastStarted = Require.nonNull("Last started", lastStarted);
    }
  
    public String getId() {
      return id.toString();
    }
  
    public String getStereotype() {
      return JSON.toJson(stereotype);
    }
  
    public String getLastStarted() {
      return DATE_TIME_FORMATTER.format(lastStarted);
    }
  }
  