JSF Restrict Page Access / Permissions - Error Parsing Issue

Question

I am trying to restrict certain pages in my web application to certain users, such as an administrator. However, I keep getting the following error:

Error Parsing: #{userSession.hasRole('ADMIN')}

I have tried several things but keep hitting a brick wall and was hoping someone may be able to shed some light.

My UserSession class has the following method:

public boolean hasRole(Role role)
{
    return roles.contains(role);
}    

I am also using the following Bean and session scope:

@ManagedBean(name="userSession")
@SessionScoped

Then, in my view, I am using:

<p:tab rendered="#{userSession.hasRole('ADMIN')}" title="Admin">

My Role class:

public class Role {

    public enum RoleType {
        ADMIN, USER
    }

    private RoleType type;

    public setRoleType(RoleType type)
    {
        this.type = type;
    }

    public RoleType getRoleType(RoleType type)
    {
        return this.type;
    }
}

As I am using a VM it's difficult for me to copy and paste my code onto here, but here are some screenshots of the stack trace:

https://i.stack.imgur.com/Slfh3.jpg

Any help is greatly appreciated.