authTokenProvider property
Callback the SDK invokes immediately before each handoff
to obtain an opaque auth token. Returning null is
allowed when the backend does not require one (e.g. a
merchant-side proxy that handles auth itself).
The callback MUST NOT log the returned token. The SDK
never logs it either - the value flows through
Authorization: Bearer ... headers on the
implementation's transport call and is held in memory
only for the lifetime of that call.
Implementation
final Future<String?> Function(GatewayTokenScope scope)? authTokenProvider;