I have two classes namely User and Role. There is many-to-many relation
between them.
class User
{
String name;
String surname;
Set roles;
}

class Role
{
String name;
}

I want to keep this relation, between User and Role, in a different
table.

user
id name surname
1 xxx yyy
2 zzz www

role
id name
1 aaa
2 bbb
3 ccc

user-role
id user_id role_id
1 1 2
2 1 3
3 2 1
4 2 2
5 2 3

How am i going to desing the mapping documents between this 2, so I can have the above 3 tables.
Thanx in advance...