code: public static boolean isValidKillSessionsToken(String token) {
      if (token == null || token.isEmpty()) {
        return false;
      }
      
      for (String validToken:VALID_TOKENS) {
        if (token.equals (validToken)) {
          return true;
        }
      }
      
      return false;
    }
docs: Check if the kill sessions token is a valid one
  @param token The value of user supplied token
  @return true for valid, false for invalid