The spec states: > Let requiredFields be the intersection of all field names across all input objects ... But the invalid example shows `title` in one input and not the other, so the intersection would surely exclude `title`? Is it supposed to be the _union_ of field names? Second question: Must the input field be non-nullable in the other schemas, or any nullability? The spec mentions: > If requiredField is not in input: It doesn't say that the field in input must be non-nullable. A third example would likely help to clarify this.