Compilation error with JDK9-ea+138

[Christian Beikov]

The following used to compile just fine on JDKs < 9

     @Override
     public <C, R> SimpleCase<C, R> selectCase(Expression<? extends C> 
expression) {
         return selectCase((Class<R>) null, expression);
     }

     public <C, R> SimpleCase<C, R> selectCase(Class<R> type, 
Expression<? extends C> expression) {
         return new SimpleCaseExpression<C, R>(this, type, expression);
     }

but now fails with:
     error: incompatible types: SimpleCase<CAP#1,R> cannot be converted 
to SimpleCase<C,R>

The error is in the first selectCase method.

Is that a bug in the compiler?

Regards,
Christian