  
      def __init__(self, child_relation=None, *args, **kwargs):
          self.child_relation = child_relation
          assert child_relation is not None, '`child_relation` is a required argument.'
          super(ManyRelatedField, self).__init__(*args, **kwargs)
          self.child_relation.bind(field_name='', parent=self)
  
      def get_value(self, dictionary):
 
</s> remove         'not_a_list': _('Expected a list of items but got type "{input_type}".')
 </s> add         'not_a_list': _('Expected a list of items but got type "{input_type}".'),
        'empty': _('This list may not be empty.')
        self.allow_empty = kwargs.pop('allow_empty', True)
  
      def __init__(self, child_relation=None, *args, **kwargs):
          self.child_relation = child_relation
        self.allow_empty = kwargs.pop('allow_empty', True)
          assert child_relation is not None, '`child_relation` is a required argument.'
          super(ManyRelatedField, self).__init__(*args, **kwargs)
          self.child_relation.bind(field_name='', parent=self)
  
      def get_value(self, dictionary):
keep keep add keep keep keep keep keep
 Added allow_empty flag for ListField, ListSerializer, ManyRelation, MultipleChoiceField. 
rest_framework/relations.py