listProviders( )

Retrieves a list of the external calendar providers for which the site supports integration.

The list of external calendar providers includes:

• External calendar providers that are supported by default, such as Google, Apple, and Microsoft.
• External calenders for which the site owner has enabled integration by installing an app.

For each external calendar provider, the list contains information about supported connection methods and features. For each provider, check features.connectMethods to find out whether to use connectByCredentials() or connectByOAuth() to establish a connection.