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

*** 278,287 ****
--- 278,288 ----
      // All 18-digit base ten strings fit into a long; not all 19-digit
      // strings will
      private static final int MAX_COMPACT_DIGITS = 18;
  
      /* Appease the serialization gods */
+     @java.io.Serial
      private static final long serialVersionUID = 6108874887143696463L;
  
      private static final ThreadLocal<StringBuilderHelper>
          threadLocalStringBuilderHelper = new ThreadLocal<StringBuilderHelper>() {
          @Override
*** 4125,4134 ****
--- 4126,4136 ----
       * Reconstitute the {@code BigDecimal} instance from a stream (that is,
       * deserialize it).
       *
       * @param s the stream being read.
       */
+     @java.io.Serial
      private void readObject(java.io.ObjectInputStream s)
          throws java.io.IOException, ClassNotFoundException {
          // Read in all fields
          s.defaultReadObject();
          // validate possibly bad fields
*** 4143,4152 ****
--- 4145,4155 ----
     /**
      * Serialize this {@code BigDecimal} to the stream in question
      *
      * @param s the stream to serialize to.
      */
+     @java.io.Serial
     private void writeObject(java.io.ObjectOutputStream s)
         throws java.io.IOException {
         // Must inflate to maintain compatible serial form.
         if (this.intVal == null)
             UnsafeHolder.setIntValVolatile(this, BigInteger.valueOf(this.intCompact));