This is normally an empty list but if additional content type aliases are passed in, any content types containing those aliases will be filtered out along with any content types that have matching property types that are included in the filtered content types

This is normally an empty list but if additional property type aliases are passed in, any content types that have these aliases will be filtered out. This is required because in the case of creating/modifying a content type because new property types being added to it are not yet persisted so cannot be looked up via the db, they need to be passed in.