### Webhook authentication
Each `WebhookConfiguration` configures exactly one authentication method used
by NOB when calling the integrator's endpoint (mutually exclusive, not
combined): mutual TLS (`MTLS`), OAuth2 client-credentials (`OAUTH2_CC`), or
a fixed set of custom headers (`CUSTOM_HEADERS`) sent with every delivery.
The three security schemes below are documented as alternatives — the
integrator's configuration determines which one actually applies.