A union type resolves to its first non-null member
The rule
Normative: this is the rule
- Where a property's type is an array of types, its lane is derived from the first member that is not
null. - An array that is empty, or that holds only
null, resolves to the sink. - Every member must itself be a JSON Schema type.
Rule identifiers are permanent and are never renumbered. Each implementation publishes its own standing against these rules; this specification does not.spec 1.0-draft · SCH-9 · changed in spec 1.0