jpa - Entity without a constraint required -

I have a unit with regard to any other person (guru) this person is null I could have thought that only the obligations. Mandatory comments compels my mentor to set up. If I remove a lot of annotations then the guardian will not be used.

  @ Entity public class extension of person model {@Id @ constraints.Required @ formats.NonEmpty public integer ID; @ManyToOne @ Obligation Essential public user user; @binding Required public string first name; @binding LastName essential public string; @ManyToOne public person advisor; ...   
 How can I have a person without a master?   
 
 
  @ManyToOne  The annotation is actually used by your GPA provider to provide "instructions" It seems that  person  in the table / relation  foreign key  (this model 1: n relations can not be advisory to B / N persons and a foreign key is null ) But with your question, I think your biz is 1: n  not required  so easily  @ManyToOne  annotation Eliminate and if someone happens to patrons, so it ties in wire through manually JPA unit manufacturer or setter method