src/java.base/share/classes/java/lang/invoke/MethodType.java

*** 102,111 ****
--- 102,112 ----
  public final
  class MethodType
          implements Constable,
                     TypeDescriptor.OfMethod<Class<?>, MethodType>,
                     java.io.Serializable {
+     @java.io.Serial
      private static final long serialVersionUID = 292L;  // {rtype, {ptype...}}
  
      // The rtype and ptypes fields define the structural identity of the method type:
      private final @Stable Class<?>   rtype;
      private final @Stable Class<?>[] ptypes;
*** 1227,1236 ****
--- 1228,1238 ----
      /// Serialization.
  
      /**
       * There are no serializable fields for {@code MethodType}.
       */
+     @java.io.Serial
      private static final java.io.ObjectStreamField[] serialPersistentFields = { };
  
      /**
       * Save the {@code MethodType} instance to a stream.
       *
*** 1249,1258 ****
--- 1251,1261 ----
       * For example, null values, or {@code void} parameter types,
       * will lead to exceptions during deserialization.
       * @param s the stream to write the object to
       * @throws java.io.IOException if there is a problem writing the object
       */
+     @java.io.Serial
      private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
          s.defaultWriteObject();  // requires serialPersistentFields to be an empty array
          s.writeObject(returnType());
          s.writeObject(parameterArray());
      }
*** 1268,1277 ****
--- 1271,1281 ----
       * @throws java.io.IOException if there is a problem reading the object
       * @throws ClassNotFoundException if one of the component classes cannot be resolved
       * @see #readResolve
       * @see #writeObject
       */
+     @java.io.Serial
      private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException {
          // Assign temporary defaults in case this object escapes
          MethodType_init(void.class, NO_PTYPES);
  
          s.defaultReadObject();  // requires serialPersistentFields to be an empty array
*** 1307,1316 ****
--- 1311,1321 ----
      /**
       * Resolves and initializes a {@code MethodType} object
       * after serialization.
       * @return the fully initialized {@code MethodType} object
       */
+     @java.io.Serial
      private Object readResolve() {
          // Do not use a trusted path for deserialization:
          //    return makeImpl(rtype, ptypes, true);
          // Verify all operands, and make sure ptypes is unshared:
          try {