inserting test data in java entity table

inserting test data in java entity table

I used Hibernate ddl generation of SQL to generate an entity's table (I
think.) Anyway, tjere's 'hashcode' field. My quesriins are:
1/ Is that field necessary? 2/ If I'm inserting test data in the table
using SQL, what do I set the value to? From wjat I read here, native java
implementation uses memory address to feed hash function? Java --
Object.hashCode() algorithm.
3/ If I wrote a mapped supperclass for all serialized entity to inherit
which performed a regular hash of the entity's 'Id' field, would I be
causing myself some grief later? (I think I got tjat idea from 'effective
java'.)