provably distinct: ? extends A should be provably distinct from Object until A is not an Object (IDEA-105695)

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/genericsHighlighting/IDEA105695.java

@@ -0,0 +1,10 @@
+import java.util.Map;
+
+public class Test {
+    void bar(Prop p) {
+         Map<? extends String, ? extends String> map = <error descr="Inconvertible types; cannot cast 'Prop' to 'java.util.Map<? extends java.lang.String,? extends java.lang.String>'">(Map<? extends String, ?  extends String>)p</error>;
+    }
+}
+
+abstract class Hashtble<K,V> implements Map<K,V> {}
+abstract class Prop extends Hashtble<Object, Object>{}