'Loads all of the references that point to this model.
We need to do this to create the ReverseReferenceProperty properties for
this model and create the <reference>_set attributes on the referenced
model, e.g.:
class Story(db.Model):
title = db.StringProperty()
class Comment(db.Model):
story = db.ReferenceProperty(Story)
story = Story.get(id)
print [c for c in story.comment_set]
In this example, the comment_set property was created based on the reference
from Comment to Story (which is inherently one to many).
Args:
model_class: Model class which will have its reference properties
initialized.
property_name: Name of property being configured.
Raises:
DuplicatePropertyError if referenced class already has the provided
collection name as a property.'

def __property_config__(self, model_class, property_name):

    super(ReferenceProperty, self).__property_config__(model_class, property_name)
    if (self.reference_class is _SELF_REFERENCE):
        self.reference_class = self.data_type = model_class
    if (self.collection_name is None):
        self.collection_name = ('%s_set' % model_class.__name__.lower())
    existing_prop = getattr(self.reference_class, self.collection_name, None)
    if (existing_prop is not None):
        if (not (isinstance(existing_prop, _ReverseReferenceProperty) and (existing_prop._prop_name == property_name) and (existing_prop._model.__name__ == model_class.__name__) and (existing_prop._model.__module__ == model_class.__module__))):
            raise DuplicatePropertyError(('Class    %s    already    has    property    %s    ' % (self.reference_class.__name__, self.collection_name)))
    setattr(self.reference_class, self.collection_name, _ReverseReferenceProperty(model_class, property_name))
