directive @nonRepeatable on OBJECT | SCALAR | INTERFACE

extend type TestObject @nonRepeatable

type TestObject @nonRepeatable {
  field: String
}

extend type TestObject @nonRepeatable

scalar Scalar @nonRepeatable

extend scalar Scalar @nonRepeatable @specifiedBy(url: "example.com")

interface Intf @nonRepeatable {
  field: String
}

extend interface Intf @nonRepeatable

type Query {
  x: Int
}