The bounty module allows registered organizations with on-chain bank accounts to register as a foundation to post bounties and supervise ongoing grant pursuits.

(Id, Id) Design Justification

"WHY so many double_maps in storage with (BountyId, BountyId)?" We use this structure for efficient clean up via double_map.remove_prefix() once a bounty needs to be removed from the storage state so that we can efficiently remove all associated state i.e. applications for a bounty or milestones submitted under a bounty