pub fn validate_reserved_metadata_key(key: &str) -> Result<(), ValidationError>Expand description
Reject a caller-supplied reserved identity/discriminator key
(mem / id / type) as metadata — the create-path half of the
reservation, deliberate and typed
(ValidationError::ReadOnlyField) rather than the incidental
UNKNOWN_METADATA_FIELD a reserved key would otherwise trip
(no installable schema can declare one). Timestamp fields are NOT
checked here: create’s posture for init_timestamp /
auto_timestamp fields is stamp-and-proceed with an
IGNORED_READONLY_FIELD warning, deliberately.