--- old/src/hotspot/share/gc/z/zForwarding.cpp	2019-04-10 18:50:23.200394500 -0400
+++ new/src/hotspot/share/gc/z/zForwarding.cpp	2019-04-10 18:50:22.296304100 -0400
@@ -69,11 +69,6 @@
     // Check for duplicates
     for (ZForwardingCursor j = i + 1; j < _entries.length(); j++) {
       const ZForwardingEntry other = at(&j);
-      if (!other.populated()) {
-        // Skip empty entries
-        continue;
-      }
-
       guarantee(entry.from_index() != other.from_index(), "Duplicate from");
       guarantee(entry.to_offset() != other.to_offset(), "Duplicate to");
     }