Regression test for scala#16727

Author: SolalPirelli

tests/pos/16727/A_1.scala

@@ -0,0 +1,3 @@
+class A:
+  extension (k: Int)
+    def getOrElse[V](default: V): V = ???

tests/pos/16727/B_2.java

@@ -0,0 +1,6 @@
+public class B_2 {
+
+  public static void test() {
+    A a = new A();
+  }
+}