Date and time of notification channel expiration, expressed as a Unix timestamp, in milliseconds. Optional.

The type of delivery mechanism used for this channel. Valid values are "web_hook" (or "webhook"). Both values refer to a channel where Http requests are used to deliver messages.

The address where notifications are delivered for this channel.

An opaque ID that identifies the resource being watched on this channel. Stable across different API versions.

A UUID or similar unique string that identifies this channel.

Identifies this as a notification channel used to watch for changes to a resource, which is "api#channel".

A Boolean value to indicate whether payload is wanted. Optional.

A version-specific identifier for the watched resource.

An arbitrary string delivered to the target address with each notification delivered over this channel. Optional.