returnPartialResponses property
Whether Dialogflow should return currently queued fulfillment response messages in streaming APIs.
If a webhook is specified, it happens before Dialogflow invokes webhook. Warning: 1) This flag only affects streaming API. Responses are still queued and returned once in non-streaming API. 2) The flag can be enabled in any fulfillment but only the first 3 partial responses will be returned. You may only want to apply it to fulfillments that have slow webhooks.
Implementation
core.bool? returnPartialResponses;