servletContext = config.getServletContext();

        encoding = config.getInitParameter(LastaPrepareFilter.ENCODING_KEY);
        if (encoding == null) {
            encoding = LastaPrepareFilter.DEFAULT_ENCODING;
        }

        // ex. sjis:Shift_JIS,eucjp:EUC-JP
        final String value = config.getInitParameter(ENCODING_MAP);
        if (StringUtil.isNotBlank(value)) {

        }

        @Override
        public ServletContext getServletContext() {
            throw new UnsupportedOperationException();
        }

        @Override
        public String getInitParameter(final String name) {
            if (SpnegoHttpFilter.Constants.LOGGER_LEVEL.equals(name)) {
                final String logLevel = getProperty(SPNEGO_LOGGER_LEVEL, StringUtil.EMPTY);