code: @SuppressWarnings("unchecked")
      @Override
      public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException,
              ServletException {
          HttpServletRequest request = (HttpServletRequest) req;
  
          String actor = null;
  
          if (userSessionAttrName != null && !userSessionAttrName.equals("")) {
              HttpSession session = request.getSession(false);
              actor = (String) session.getAttribute("userSessionAttrName");
          }
          String ipAddress = request.getRemoteAddr();
          String url = request.getRequestURL().toString();
  
          EventBuilder builder = new EventBuilder();
          builder.addAction(url).addOrigin(ipAddress);
          if (actor == null) {
              builder.addActor(ipAddress);
          } else {
              builder.addActor(actor + "[" + ipAddress + "]");
          }
  
          Map<String, String[]> params = req.getParameterMap();
  
          for (final Map.Entry<String, String[]> entry : params.entrySet()) {
              builder.addField(entry.getKey(), entry.getValue());
          }
  
          AuditManager.getInstance().audit(builder.build());
          chain.doFilter(req, res);
      }
docs: /*
  (non-Javadoc)
  
  @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest,
  javax.servlet.ServletResponse, javax.servlet.FilterChain)