              try:
                  default = field.get_default()
              except SkipField:
                  continue
              defaults[field.field_name] = default
  
          return defaults
  
      def run_validators(self, value):
          """
 
</s> remove             field_name: attrs[field_name]
            for field_name in self.fields
 </s> add             source: attrs[source]
            for source in sources </s> remove         class MockSerializer:
            def __init__(self, instance):
                self.instance = instance

 </s> add  </s> remove         serializer = MockSerializer(instance=self.instance)
 </s> add         serializer = UniquenessTogetherSerializer(instance=self.instance) </s> remove             for field_name in self.fields:
                if field_name not in attrs:
                    attrs[field_name] = getattr(serializer.instance, field_name)
 </s> add             for source in sources:
                if source not in attrs:
                    attrs[source] = getattr(serializer.instance, source)
            defaults[field.source] = default
              try:
                  default = field.get_default()
              except SkipField:
                  continue
            defaults[field.source] = default
  
          return defaults
  
      def run_validators(self, value):
          """
keep keep keep keep replace keep keep keep keep keep
 Fix UniqueTogetherValidator with field sources (#7086)

* Add failing tests for unique_together+source

* Fix UniqueTogetherValidator source handling

* Fix read-only+default+source handling

* Update test to use functional serializer

* Test UniqueTogetherValidator error+source 
rest_framework/serializers.py