jpa spring prevent insert one to many code example

Example: one to one best practices

@Entity(name = "Post")
@Table(name = "post")
public class Post {
 
    @Id
    @GeneratedValue
    private Long id;
 
    private String title;
 
    @OneToOne(mappedBy = "post", cascade = CascadeType.ALL, 
              fetch = FetchType.LAZY, optional = false)
    private PostDetails details;
 
    //Getters and setters omitted for brevity
 
    public void setDetails(PostDetails details) {
        if (details == null) {
            if (this.details != null) {
                this.details.setPost(null);
            }
        }
        else {
            details.setPost(this);
        }
        this.details = details;
    }
}