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 java.util.Arrays;
  import java.util.Collections;
  import java.util.Set;
  import java.util.TreeSet;
  
  public class StandardGridRoles {
    private StandardGridRoles() {
      // Constants
    }
  
    public static final Role DISTRIBUTOR_ROLE = Role.of("grid-distributor");
    public static final Role EVENT_BUS_ROLE = Role.of("grid-event-bus");
    public static final Role HTTPD_ROLE = Role.of("httpd");
    public static final Role NODE_ROLE = Role.of("grid-node");
    public static final Role ROUTER_ROLE = Role.of("grid-router");
    public static final Role SESSION_MAP_ROLE = Role.of("grid-session-map");
    public static final Role SESSION_QUEUE_ROLE = Role.of("grid-new-session-queue");
  
    public static final Set<Role> ALL_ROLES =
        Collections.unmodifiableSet(
            new TreeSet<>(
                Arrays.asList(
                    DISTRIBUTOR_ROLE,
                    EVENT_BUS_ROLE,
                    NODE_ROLE,
                    ROUTER_ROLE,
                    SESSION_MAP_ROLE,
                    SESSION_QUEUE_ROLE)));
  }
  