Always present for WebhookRequest. Ignored for WebhookResponse. The unique identifier of the session. This field can be used by the webhook to identify a session. Format: projects/<ProjectID>/locations/<LocationID>/agents/<AgentID>/sessions/<SessionID> or projects/<ProjectID>/locations/<LocationID>/agents/<AgentID>/environments/<EnvironmentID>/sessions/<SessionID> if environment is specified.
Optional for WebhookRequest. Optional for WebhookResponse. All parameters collected from forms and intents during the session. Parameters can be created, updated, or removed by the webhook. To remove a parameter from the session, the webhook should explicitly set the parameter value to null in WebhookResponse. The map is keyed by parameters' display names.
An object containing a list of "key": value pairs. Example: { "name": "wrench", "mass": "1.3kg", "count": "3" }.