UserEntity.java

public class UserEntity extends EventSourcedBehavior<UserCommand, UserEvent, User> {
  
  @Override
  public CommandHandler<UserCommand, UserEvent, User> commandHandler() {
    return newCommandHandlerBuilder().forAnyState()             
      .onCommand(UserCommand.class, (user, command) -> {
        
        List<UserEvent> events = user.process(command);
        
        return Effect()
          .persist(events)
          .thenReply(command.replyTo(), user -> CommandProcessed.of());
      })
      .build();
  }
  
  @Override
  public EventHandler<User, UserEvent> eventHandler() {
    return newEventHandlerBuilder().forAnyState()
      
      .onEvent(UserEvent.class, (user, event) -> user.apply(event))
     
      .build();
  }
}