--- old/src/java.base/share/classes/jdk/internal/reflect/UnsafeFieldAccessorImpl.java	2018-07-05 23:11:54.000000000 -0700
+++ new/src/java.base/share/classes/jdk/internal/reflect/UnsafeFieldAccessorImpl.java	2018-07-05 23:11:54.000000000 -0700
@@ -27,6 +27,8 @@
 
 import java.lang.reflect.Field;
 import java.lang.reflect.Modifier;
+import java.util.Objects;
+
 import jdk.internal.misc.Unsafe;
 
 /** Base class for jdk.internal.misc.Unsafe-based FieldAccessors. The
@@ -38,20 +40,31 @@
 
 abstract class UnsafeFieldAccessorImpl extends FieldAccessorImpl {
     static final Unsafe unsafe = Unsafe.getUnsafe();
+    private static final int FLATTENABLE = 0x01;
+    private static final int FLATTENED   = 0x10;
+    private static final int NULLABLE    = 0x100;
 
     protected final Field   field;
     protected final long    fieldOffset;
     protected final boolean isFinal;
-    protected final boolean isFlattened;
+    protected final int     flags;
 
     UnsafeFieldAccessorImpl(Field field) {
         this.field = field;
         if (Modifier.isStatic(field.getModifiers()))
-            fieldOffset = unsafe.staticFieldOffset(field);
+            this.fieldOffset = unsafe.staticFieldOffset(field);
         else
-            fieldOffset = unsafe.objectFieldOffset(field);
-        isFinal = Modifier.isFinal(field.getModifiers());
-        isFlattened = ReflectionFactory.langReflectAccess().isFlattened(field);
+            this.fieldOffset = unsafe.objectFieldOffset(field);
+        this.isFinal = Modifier.isFinal(field.getModifiers());
+
+        int flags = 0;
+        if (ReflectionFactory.langReflectAccess().isFlattenable(field))
+            flags |= FLATTENABLE;
+        if (ReflectionFactory.langReflectAccess().isFlattened(field))
+            flags |= FLATTENED;
+        if (ReflectionFactory.langReflectAccess().isNullable(field))
+            flags |= NULLABLE;
+        this.flags = flags;
     }
 
     protected void ensureObj(Object o) {
@@ -61,6 +74,30 @@
         }
     }
 
+    protected boolean isFlattenable() {
+        return (flags & FLATTENABLE) == FLATTENABLE;
+    }
+
+    protected boolean isFlattened() {
+        return (flags & FLATTENED) == FLATTENED;
+    }
+
+    protected boolean isNullable() {
+        return (flags & NULLABLE) == NULLABLE;
+    }
+
+    protected Object checkValue(Object value) {
+        if (!isNullable() && value == null)
+            throw new NullPointerException(field + " cannot be set to null");
+
+        if (value != null) {
+            if (!field.getType().isAssignableFrom(value.getClass())) {
+                throwSetIllegalArgumentException(value);
+            }
+        }
+        return value;
+    }
+
     private String getQualifiedFieldName() {
       return field.getDeclaringClass().getName() + "." +field.getName();
     }