java - Ebean ManyToOne nullable join -

i have 2 models :

@entity  @table(name="table_entry") public class tableentry extends model {          @manytoone(fetch=fetchtype.lazy)         @joincolumn(name="clone_id", referencedcolumnname="clone_id")         public genedata gene_data;          @id         @generatedvalue(strategy = generationtype.identity)         public long id;          @constraints.required         public string strain;         public string clone_id;         public string exp_type;         ... 

and

@entity  @table(name="gene_data") public class genedata extends model {     @id     @generatedvalue(strategy = generationtype.identity)     public long id;      @manytoone      public list<tableentry> entry;      public string clone_id;         public string gene_name;         public string wb_id;         ... 

i join table_entry on clone_id. however, not every row in table_entry has row in gene_data. want gene_data null when not found during join. possible?

what doing wrong? keep getting error

we got following error:  referential integrity constraint violation:  "fk_table_entry_gene_data_1:  public.table_entry foreign key(clone_id) references  public.gene_data(clone_id) ('y56a3a.19')"; 

i think there row in table_entry clone_id set 'y56a3a.19' there isn't row in gene_data value.