code: public void init(FilterConfig filterConfig) throws ServletException {
          this.config = filterConfig;
          this.errorLogging = isBooleanParameter(filterConfig, "errorLogging", true);
          setupExceptExtSet(filterConfig);
          setupExceptUrlPattern(filterConfig);
          setupRequestUriTitleUrlPattern(filterConfig);
          setupSubRequestUrlPatternUrlPattern(filterConfig);
          setupRequestCharacterEncoding(filterConfig);
          setupMaskParamSet(filterConfig);
          setupMaskedString(filterConfig);
      }
docs: ==========