Firebase-admin

Cloud Messaging

- [Feature] Introduced a series of new parameters to the [`AndroidNotification`](https://godoc.org/firebase.google.com/go/messaging#AndroidNotification) type.

Authentication

- [Fixed] Fixed a bug in the `TenantIterator` type which was preventing it from listing all the tenants correctly.

Authentication

- [Fixed] Minor improvements to the implementation to fix the API reference output generated by `godoc`.

- Dropped support for Go 1.9 and 1.10. The Admin SDK for Go now requires Go 1.11 or higher. Thanks [shogo82148](https://github.com/shogo82148) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/294).

Firebase Auth

- Added a new `IsInvalidEmail()` error checking function. Thanks [shogo82148](https://github.com/shogo82148) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/299).
- Added `auth.TenantManager` API for creating, updating, retrieving, and deleting authentication tenants.
- Added `auth.TenantClient` API for managing users, configuring SAML/OIDC providers, and generating email action links for specific tenants.

Firebase Cloud Messaging

- Batch messaging APIs `SendAll()` and `SendMulticast()` now support sending up to 500 messages in a single call.

Firebase Auth

- Fixed `auth.ExportedUserRecord` no longer exposes password hashes that are redacted due to lack of permissions in the service account credentials.
- Added `auth.OIDCProviderConfig` type and the related functions to create, retrieve, update and delete OIDC auth provider configurations.
- Added `auth.SAMLProviderConfig` type and the related functions to create, retrieve, update and delete SAML auth provider configurations.

Firebase Cloud Messaging

- Added support for sending an image URL with notifications. Thanks [chemidy](https://github.com/chemidy) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/261).

Cloud Messaging

- Added the [`SendAll()`](https://godoc.org/firebase.google.com/go/messaging#Client.SendAll) API for sending multiple notifications as a batch.
- Added `MulticastMessage` and [`SendMulticast()`](https://godoc.org/firebase.google.com/go/messaging#Client.SendMulticast) APIs for sending notifications to multiple recipients.
- Added support for specifying the analytics label for notifications via `AndroidFCMOptions`, `APNSFCMOptions` and `FCMOptions` types. Thanks [chemidy](https://github.com/chemidy) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/256).

- Fixed some unit tests that were failing in environments without Google Application Default credentials.