Create two classes, compile and put them in base and v10 directories respectively 
public class C { 
   public void m(){} 
} 

public class C { 
   public class Inner{ public void k(){} }
   public void m(){} 
} 

create MR jar 
jar cf file.jar -C base C.class, 
                --release 10 -C v10 C.class 

jar tool exits successfully.