8039520: More atomicity of atomic updates

Reviewed-by: dl, skoivu, igerasim
diff --git a/jdk/src/share/classes/java/util/concurrent/atomic/AtomicReferenceFieldUpdater.java b/jdk/src/share/classes/java/util/concurrent/atomic/AtomicReferenceFieldUpdater.java
index f0a0840..4408ff3 100644
--- a/jdk/src/share/classes/java/util/concurrent/atomic/AtomicReferenceFieldUpdater.java
+++ b/jdk/src/share/classes/java/util/concurrent/atomic/AtomicReferenceFieldUpdater.java
@@ -334,6 +334,8 @@
 
             if (vclass != fieldClass)
                 throw new ClassCastException();
+            if (vclass.isPrimitive())
+                throw new IllegalArgumentException("Must be reference type");
 
             if (!Modifier.isVolatile(modifiers))
                 throw new IllegalArgumentException("Must be volatile type");