# Package org.optaplanner.core.api.domain.entity

Domain annotations and support classes for a planning entity.

- Interface Summary
  Interface | Description
  --- | ---
  PinningFilter<Solution_,​Entity_> | Decides on accepting or discarding a `PlanningEntity`.
  PlanningEntity.NullDifficultyComparator | Workaround for annotation limitation in `PlanningEntity.difficultyComparatorClass()`.
  PlanningEntity.NullDifficultyWeightFactory | Workaround for annotation limitation in `PlanningEntity.difficultyWeightFactoryClass()`.
  PlanningEntity.NullPinningFilter | Workaround for annotation limitation in `PlanningEntity.pinningFilter()` ()}.

- Annotation Types Summary
  Annotation Type | Description
  --- | ---
  PlanningEntity | Specifies that the class is a planning entity.
  PlanningPin | Specifies that a boolean property (or field) of a `PlanningEntity` determines if the planning entity is pinned.