import java.util.Map;

class MyAnnotatedTypeMirror {
    void addAnnotations() {}
}

class MyAnnotatedTypeVariable extends MyAnnotatedTypeMirror {}

public class CastTypeVariable {
    public static <K extends MyAnnotatedTypeMirror, V extends MyAnnotatedTypeMirror> V mapGetHelper(
            Map<K, V> mappings, MyAnnotatedTypeVariable key) {
        V possValue = (V) mappings.get(key);
        // :: error: (dereference.of.nullable)
        possValue.addAnnotations();
        return possValue;
    }
}
