| Class | BaseBranchMergeQueue | Common methods for both the single and multi branch queues. | 
| Class | SingleBranchMergeQueue | A branch merge queue contains proposals from one or more branches. | 
| Class | MultiBranchMergeQueue | A database entity used to group branches proposals together. | 
| Class | BranchMergeQueueSet | A utility for getting queues. |