message: Set default Entity
  For the Entity Collection, set a default Entity to allow its usage as a
  static method return type
diff: * abstract interface.
  * @typeParam T - The type of Entities in the EntityCollection
  */
  -declare abstract class EntityCollection<T extends Entity>
  +declare abstract class EntityCollection<T extends Entity = Entity>
  extends Collection<T> {
  /**
  * The source data is, itself, a mapping of IDs to data objects
  