code: protected void checkApiToken(String apiToken) {
          if (StringUtils.isBlank(apiToken)) throw new MissingApiTokenException("Empty key");
          if (apiToken.length() != TOKEN_LENGTH) throw new MissingApiTokenException("Wrong length");
          if (!apiToken.matches(HEX_PATTERN)) throw new MissingApiTokenException("Not a HEX value");
      }
docs: Syntax checks the API Token.
  
  @param apiToken value to check
  @throws IllegalArgumentException if invalid