@SuppressWarnings("checkstyle:BooleanExpressionComplexity")
    public static boolean isTrue(ServletRequest request, String paramName) {
        String value = getCleanParam(request, paramName);
        return value != null
                && (value.equalsIgnoreCase("true")
                || value.equalsIgnoreCase("t")
                || value.equalsIgnoreCase("1")
                || value.equalsIgnoreCase("enabled")
                || value.equalsIgnoreCase("y")
                || value.equalsIgnoreCase("yes")
                || value.equalsIgnoreCase("on"));
    }
<p>Checks to see if a request param is considered true using a loose matching strategy for
general values that indicate that something is true or enabled, etc.</p>
<p/>
<p>Values that are considered "true" include (case-insensitive): true, t, 1, enabled, y, yes, on.</p>

@param request   the servlet request
@param paramName @return true if the param value is considered true or false if it isn't.
@return true if the given parameter is considered "true" - false otherwise.
web/src/main/java/org/apache/shiro/web/util/WebUtils.java