diff -r 7efe5923cfdc -r 01905d6a828b src/hotspot/share/runtime/arguments.cpp
--- a/src/hotspot/share/runtime/arguments.cpp	Wed Sep 04 13:06:04 2019 +0200
+++ b/src/hotspot/share/runtime/arguments.cpp	Wed Sep 04 13:06:44 2019 +0200
@@ -628,14 +628,7 @@
   }
 }
 
-extern bool lookup_special_flag_ext(const char *flag_name, SpecialFlag& flag);
-
 static bool lookup_special_flag(const char *flag_name, SpecialFlag& flag) {
-  // Allow extensions to have priority
-  if (lookup_special_flag_ext(flag_name, flag)) {
-    return true;
-  }
-
   for (size_t i = 0; special_jvm_flags[i].name != NULL; i++) {
     if ((strcmp(special_jvm_flags[i].name, flag_name) == 0)) {
       flag = special_jvm_flags[i];