The `source` argument is not meaningful when applied to a `child=` field. Remove `source=` from the field declaration.
In !2018 (merged) we changed the serializer for the MultipleSelectFieldType
.
We, unfortunately, did not have a test to confirm whether the new feature of the user_field_names
parameter would work when set to either True
or False.
When we set it to True
, the source
parameter was automatically set for every serializer. However, this caused an issue because the source
parameter cannot be passed to the child
argument.