static final variable in non-static Inner class

[Prakash Rai]

class Otr{
    
   class Inr{
   static int a=10;//not allowed 
   static final int b=20;// is allowed WHY?
   }
}

As we say that static declaration is not Allowed in Non-static Inner class . Then why static final variable is allowed?

[Jeff Verdegan]

Because the compiler can get rid of the variable and just replace all uses of it with the constant.