The set of entity types that this predicate uses to filter a list of TrashItems.
When this predicate is used in a ListFilter, only the TrashItems containing
deleted Artifacts of one of the types in this set will be returned. The set
of types returned is immutable.
Below are examples in XML formats. All examples are shown with all inherited members. Quoting when required is part of the examples, but you must obviously populate with your own data.