How concatenate two string in Spring Expression Language (SpEL)

In my spring application, the methods from my controller and service classes have this annotation to security purposes:

@PreAuthorize("hasPermission(#user, 'cadastra')")

the second argument, the permission, should have this format:

<<action_name>>_<<class_name>>

What expression I should use to accomplish that, taking in consideration the class name is held by this.getClass().getName()?

I finally solve this. I add a new method in my controller:

public String getName() {
    String nome_classe = entityClass.getSimpleName();
    System.out.println("getName nome_class = "+nome_classe);
    return nome_classe;
}

and now I use the annotation in that way:

@PreAuthorize("hasPermission(#user, 'cadastra_'+#this.this.name)")