protected String getInitParam(String paramName) {
        FilterConfig config = getFilterConfig();
        if (config != null) {
            return StringUtils.clean(config.getInitParameter(paramName));
        }
        return null;
    }
Returns the value for the named {@code init-param}, or {@code null} if there was no {@code init-param}
specified by that name.

@param paramName the name of the {@code init-param}
@return the value for the named {@code init-param}, or {@code null} if there was no {@code init-param}
specified by that name.
web/src/main/java/org/apache/shiro/web/servlet/AbstractFilter.java