In my instance I was provisioning out the ISC name field (which i know is unique) so after the create action i do a query to go and find the db generated id field.
account.setNativeIdentity lets you send it back to ISC.
//Get the new native identity value
insertedUser = connection.prepareStatement("Select id from <table> where [name] = ?");
insertedUser.setString(1, identityName);
ResultSet rs = insertedUser.executeQuery();
String retrievedId = null;
while (rs.next()) {
retrievedId = rs.getString("id");
}
account.setNativeIdentity(retrievedId);