This change record applies only from Drupal 8.x-dev to Drupal 8.x-dev. If you are looking for Drupal 7.x to 8.x change records you may safely skip it.
ContentEntityBase::getPropertyDefinitions()
is replaced by ContentEntityBase::getFieldDefinitions()
, just as ContentEntityBase::getPropertyDefinition($name)
is replaced by ContentEntityBase::getFieldDefinition($name)
Besides that it is now possible to retrieve metadata from entities and their fields without having to instantiate their data objects. Check the issue summary of #2002134: Move TypedData metadata introspection from data objects to definition objects for a related list of API changes and an usage example.