I'm sure this is a question that would have been asked many many times. However, I could not find one that suites my situation . Please help.

I have 2 tables parent and child. Structure as below

Parent
------
ID
Name

Child
-----
ID
Dttm
Name
xyz
abc

Java for Parent
-----------
Class Parent{
private long ID;
private String Name;
Set <Child> children;
} with getters and setters

Its a one to many relationship from parent to child. Parent's PK is ID generated through a sequence and child should use the same ID (same sequence number generated for parent). ID and Dttm (date time) makes the unique key on the child. When i insert a parent with the set filled for child i need to be able to cascade the save. How does the hbm mapping look for this situation ?