src/java.base/share/classes/java/math/BigInteger.java

*** 4602,4611 ****
--- 4602,4612 ----
          }
          return fn;
      }
  
      /** use serialVersionUID from JDK 1.1. for interoperability */
+     @java.io.Serial
      private static final long serialVersionUID = -8287574255936472291L;
  
      /**
       * Serializable fields for BigInteger.
       *
*** 4620,4629 ****
--- 4621,4631 ----
       * @serialField firstNonzeroByteNum int
       *              appears in the serialized form for backward compatibility
       * @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),
          new ObjectStreamField("bitCount", Integer.TYPE),
          new ObjectStreamField("bitLength", Integer.TYPE),
*** 4641,4650 ****
--- 4643,4653 ----
       * bitLengthPlusOne and lowestSetBitPlusTwo, to 0 rather than some other
       * marker value. Therefore, no explicit action to set these fields needs to
       * 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
          ObjectInputStream.GetField fields = s.readFields();
  
*** 4707,4716 ****
--- 4710,4720 ----
       * {@code bitCount}, {@code bitLength}, {@code lowestSetBit}, and
       * {@code firstNonzeroByteNum}, respectively.  These values are compatible
       * 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();
          fields.put("signum", signum);
          fields.put("magnitude", magSerializedForm());