How to use session in EL?

Question

I have a class WebUtil and below method is inside it.

public static String  getOtp(HttpSession session){
    String val = getAttribute(session, AppAttr.OTP_MSG);
    if(val != null){
        session.removeAttribute(AppAttr.OTP_MSG.key);
    }
    return val;
}

I have mapped this method in a .tld file and want to use it in my jsp. Below 'util' is the prefix for the tld.

${util:getOtp(session)}

But the value of 'session' is null in the java method.

Any help would be appreciated.

Thanks in advance