--- old/src/hotspot/share/gc/z/zBarrierSet.cpp	2020-05-29 12:04:25.000000000 +0200
+++ new/src/hotspot/share/gc/z/zBarrierSet.cpp	2020-05-29 12:04:25.000000000 +0200
@@ -95,3 +95,7 @@
   // Flush and free any remaining mark stacks
   ZHeap::heap()->mark_flush_and_free(thread);
 }
+
+void ZBarrierSet::print_on(outputStream* st) const {
+  st->print_cr("ZBarrierSet");
+}