Java unique_ptr test ownership enhancement to test

Make sure the object is owned before releasing ownership
and passing ownership to unique_ptr instance.

Examples/test-suite/cpp11_std_unique_ptr.i

@@ -63,6 +63,10 @@ bool is_nullptr(Klass *p) {
   return p == nullptr;
 }
 
+Klass *get_not_owned_ptr(Klass *p) {
+  return p;
+}
+
 std::unique_ptr<Klass> makeKlassUniquePtr(const char* label) {
   return std::unique_ptr<Klass>(new Klass(label));
 }

Examples/test-suite/java/cpp11_std_unique_ptr_runme.java

@@ -63,6 +63,21 @@ public class cpp11_std_unique_ptr_runme {
       checkCount(0);
     }
 
+    {
+      Klass kin = new Klass("KlassInput");
+      boolean exception_thrown = false;
+      try {
+        Klass notowned = cpp11_std_unique_ptr.get_not_owned_ptr(kin);
+        cpp11_std_unique_ptr.takeKlassUniquePtr(notowned);
+      } catch (RuntimeException e) {
+        exception_thrown = true;
+      }
+      if (!exception_thrown)
+        throw new RuntimeException("Should have thrown 'Cannot release ownership as memory is not owned' error");
+      kin.delete();
+      checkCount(0);
+    }
+
     {
       KlassInheritance kini = new KlassInheritance("KlassInheritanceInput");
       checkCount(1);