--- old/src/hotspot/share/classfile/packageEntry.cpp	2020-08-31 08:10:36.338515842 -0700
+++ new/src/hotspot/share/classfile/packageEntry.cpp	2020-08-31 08:10:36.114507410 -0700
@@ -245,6 +245,7 @@
 }
 
 static int compare_package_by_name(PackageEntry* a, PackageEntry* b) {
+  assert(a == b || a->name() != b->name(), "no duplicated names");
   return a->name()->fast_compare(b->name());
 }