code: static void throwIfUnrecognizedParamName(Enumeration initParamNames) throws ServletException {
          final Set<String> recognizedParameterNames = new HashSet<String>();
          recognizedParameterNames.add(ALLOW_MULTI_VALUED_PARAMETERS);
          recognizedParameterNames.add(PARAMETERS_TO_CHECK);
          recognizedParameterNames.add(ONLY_POST_PARAMETERS);
          recognizedParameterNames.add(CHARACTERS_TO_FORBID);
          recognizedParameterNames.add(LOGGER_HANDLER_CLASS_NAME);
  
          while (initParamNames.hasMoreElements()) {
              final String initParamName = (String) initParamNames.nextElement();
              if (!recognizedParameterNames.contains(initParamName)) {
                  FilterUtils.logException(LOGGER, new ServletException("Unrecognized init parameter [" + initParamName + "].  Failing safe.  Typo" +
                          " in the web.xml configuration? " +
                          " Misunderstanding about the configuration "
                          + RequestParameterPolicyEnforcementFilter.class.getSimpleName() + " expects?"));
              }
          }
      }
docs: Examines the Filter init parameter names and throws ServletException if they contain an unrecognized
  init parameter name.
  <p>
  This is a stateless static method.
  <p>
  This method is an implementation detail and is not exposed API.
  This method is only non-private to allow JUnit testing.
  
  @param initParamNames init param names, in practice as read from the FilterConfig.
  @throws ServletException if unrecognized parameter name is present