--- old/src/java.base/share/classes/java/math/BigInteger.java	2019-08-27 17:27:54.874324386 -0700
+++ new/src/java.base/share/classes/java/math/BigInteger.java	2019-08-27 17:27:54.674324386 -0700
@@ -4604,6 +4604,7 @@
     }
 
     /** use serialVersionUID from JDK 1.1. for interoperability */
+    @java.io.Serial
     private static final long serialVersionUID = -8287574255936472291L;
 
     /**
@@ -4622,6 +4623,7 @@
      * @serialField lowestSetBit int
      *              appears in the serialized form for backward compatibility
      */
+    @java.io.Serial
     private static final ObjectStreamField[] serialPersistentFields = {
         new ObjectStreamField("signum", Integer.TYPE),
         new ObjectStreamField("magnitude", byte[].class),
@@ -4643,6 +4645,7 @@
      * be taken in readObject because those fields already have a 0 value by
      * default since defaultReadObject is not being used.
      */
+    @java.io.Serial
     private void readObject(java.io.ObjectInputStream s)
         throws java.io.IOException, ClassNotFoundException {
         // prepare to read the alternate persistent fields
@@ -4709,6 +4712,7 @@
      * with older implementations, but will be ignored by current
      * implementations.
      */
+    @java.io.Serial
     private void writeObject(ObjectOutputStream s) throws IOException {
         // set the values of the Serializable fields
         ObjectOutputStream.PutField fields = s.putFields();