How to deserialize Json with a nested array of objects in a simple Spring Boot application

The Json POST request looks like this:

   {
   'title':'Star Wars: The Empire Strikes Back',
   'description':'Darth Vader is adamant about turning Luke Skywalker to the dark side.',
   'actors':[
      {
         'lastName':'Ford',
         'name':'Harrison'
      },
      {
         'lastName':'Hamill',
         'name':'Mark'
      }
   ]
  }

So my Spring Boot Application just wants to store this whole json as a "Film" class and inside it has an inline array of "Actors". Here is the Film model:

    @Entity
    public class Film {

	  @Id
      @GeneratedValue
      private long id;
	  private String title;
	  private String description;
	
	  private ArrayList<Actor> actors = new ArrayList<>();

I have a separate entity for the Actor that looks similar:

    @Entity
    public class Actor {

	  @Id
      @GeneratedValue
      private long id;
	  private String name;
	  private String lastName;

Finally, I am using the RequestBody Annotation in the PostMapping in the Controller:

    @PostMapping(value= "/api/film")
	@ResponseStatus(HttpStatus.CREATED)
	public Film addFilm(@RequestBody Film film) {
       service.createFilm(film);
	   return film;

The problem is I always get the java.io.NotSerializableException that Actor cannot be serialized. I tried making Actor a Static inline class but that did not change anything. Anyone have an idea what is wrong here ?

Your Actor class needs to implement Serializable.

@Entity
public class Actor implements Serializable{

  @Id
  @GeneratedValue
  private long id;
  private String name;
  private String lastName;