      and should instead simply set 'many=True' on the relationship.
      """
      initial = []
      default_empty_html = []
  
      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)
 
</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.')
    default_error_messages = {
        'not_a_list': _('Expected a list of items but got type "{input_type}".'),
        'empty': _('This list may not be empty.')
    }
      and should instead simply set 'many=True' on the relationship.
      """
      initial = []
      default_empty_html = []
    default_error_messages = {
        'not_a_list': _('Expected a list of items but got type "{input_type}".'),
        'empty': _('This list may not be empty.')
    }
  
      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)
keep keep keep add keep keep keep keep keep keep
 Added allow_empty flag for ListField, ListSerializer, ManyRelation, MultipleChoiceField. 
rest_framework/relations.py