1{ 2 "$schema": "https://json-schema.org/draft/2020-12/schema", 3 "properties": { 4 "myArray": { 5 "type": "array", 6 "maxContains": 1, 7 "contains": {"properties": {"itemType": {"const": "type A"}} 8 }, 9 "items": {"properties": {"itemType": {"type": "string"}}} 10 } 11 } 12}