Only add instance to collection association if it has a primary key
Remove logic duplication of adding instances to collection associations
Add test for saving association adding to collection with primary key
Add test for updating instance with primary key being added to collection association
Allow configuration of belongsTo association to add it to collection association without primary key
Merge pull request #1 from brettshollenberger/features/add-to-collection-association-only-with-primary-key

Features/add to collection association only with primary key