code: @VisibleForTesting
    public static boolean register(PropertyKey key) {
      String name = key.getName();
      String[] aliases = key.getAliases();
      if (DEFAULT_KEYS_MAP.containsKey(name)) {
        if (DEFAULT_KEYS_MAP.get(name).isBuiltIn() || !key.isBuiltIn()) {
          return false;
        }
      }
      DEFAULT_KEYS_MAP.put(name, key);
      if (aliases != null) {
        for (String alias : aliases) {
          DEFAULT_ALIAS_MAP.put(alias, key);
        }
      }
      return true;
    }
docs: Registers the given key to the global key map.
  
  @param key th property
  @return whether the property key is successfully registered