title: use Enum class instead of a Map for holding constants
body: <p>I have a map like below to hold some constant values. Keeping values in a Map is not a good practice. Instead I can use an enum to hold these values.
  But I'm a bit confused about how to create an enum for the below mapping</p>
  
  <pre><code>//Map to store the events
  public static final Map&lt;String, Integer[]&gt; OLYMPICS_SPORT_ID_PARAMS = new HashMap&lt;&gt;();
  public static final Map&lt;String, Integer[]&gt; OLYMPICS_EVENT_ID_PARAMS = new HashMap&lt;&gt;();
  public static final Map&lt;String, Integer[]&gt; OLYMPICS_PHASE_ID_PARAMS = new HashMap&lt;&gt;();
  static {
      OLYMPICS_SPORT_ID_PARAMS.put("sportId", VALID_SPORT_IDS);
      OLYMPICS_EVENT_ID_PARAMS.put("n_EventID", VALID_EVENT_IDS);
      OLYMPICS_PHASE_ID_PARAMS.put("n_EventPhaseID", VALID_EVENT_PHASE_IDS);
  }
  
  public static final Map&lt;String, Map&lt;String, Integer[]&gt;&gt; OLYMPICS_EVENTS_MAP = new HashMap&lt;&gt;();
  static {
      OLYMPICS_EVENTS_MAP.put("sportId", OLYMPICS_SPORT_ID_PARAMS);
      OLYMPICS_EVENTS_MAP.put("eventId", OLYMPICS_EVENT_ID_PARAMS);
      OLYMPICS_EVENTS_MAP.put("eventPhaseId", OLYMPICS_PHASE_ID_PARAMS);
  }
  </code></pre>
  
  <p>Any idea to create an ENUM class to map OLYMPICS_EVENTS_MAP ?</p>