If a class is given, this function registers an unnamed CMS object class under
  the given name. Otherwise,
  Scrivito.provideObjClass generates an object class using the
  given definition.
  Object classes serve as boilerplates for CMS objects. Their main purpose is to
  define the attributes the instances require, for example a
  string attribute named “title”, or a
  binary attribute for binary data like an image or a PDF document.