Empty union regarded as invalid schema.
leehambley opened this issue · comments
The GraphQL spec's grammar permits empty unions, but a point follows which says that an empty union is invalid. The Apollo Federation spec requires the definition of a union _Entity (no members).
It's not clear to me whether the graphql-schema-linter should forbid this at parse time, or whether it should be a rule we can disable separately.
There's a similar issue here #151
The Federated Schema spec from Apollo actually clarifies that this empty union can be omitted if no types are really federated:
