The value of this keyword MUST be an array. This array MUST have at least one element. Elements of this array MUST be strings, and MUST be unique.
An object instance is valid against this keyword if its property set contains all elements in this keyword's array value.
https://datatracker.ietf.org/doc/html/draft-wright-json-schema-validation-00#section-5.15
See Implementation
The value of this keyword MUST be an array. This array MUST have at least one element. Elements of this array MUST be strings, and MUST be unique.
An object instance is valid against this keyword if its property set contains all elements in this keyword's array value.