Best practice and implementation of a builder pattern when using JPA

I have a class that is suitable for a builder pattern, there are many params and I'd rather not use a ton of telescopic constructors.

My problem is that this class is a JPA entity and that is very new to me.

Having private final data members is throwing an error as I they are not initialised in the constructor and as far as I'm aware, JPA requires an empty protected constructor.

Can anyone help please? An example would be fantastic, I've included a basic example of the code below but it's very generic. I've emoted many of the accessors and data members to save space/time.

  @Entity//(name= "TABLE_NAME") //name of the entity / table name
public class Bean implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id //primary key
    @GeneratedValue
    Long id;
    private final DateTime date;
    private final String title;
    private final String intro;


    //used by jpa
    protected Bean(){}

    private Bean(Bean Builder beanBuilder){
        this.date = beanBuilder;
        this.title = beanBuilder;

        this.intro = beanBuilder;
    }

    public DateTime getDate() {
        return date;
    }

    public String getTitle() {
        return title;
    }

    public static class BeanBuilder Builder{

        private final DateTime date;
        private final String title; 

        //private optional 

        public BeanBuilder(DateTime date, String title) {
            this.date = date;
            this.title = title;
        }

        public BeanBuilder intro(String intro){
            this.intro = intro;
            return this;
        }

        public BeanBuilder solution(String solution){
            this.intro = solution;
            return this;
        }

        public Bean buildBean(){
            return new Bean(this);
        }

    }

}