$extensions MUST be an object keyed by vendor (§5.2.3, §6.3.2). Keys SHOULD use reverse domain notation, so a key without a dot is a warning. Values are any JSON and are not inspected by the validator.
$extensions
$extensionsMUST be an object keyed by vendor (§5.2.3, §6.3.2). Keys SHOULD use reverse domain notation, so a key without a dot is a warning. Values are any JSON and are not inspected by the validator.