Values:
RESPONSE_TYPE_UNSPECIFIED (0):
Not specified.
ENTRY_PROMPT (1):
The response is from an [entry
prompt][google.cloud.dialogflow.cx.v3.Page.entry_fulfillment]
in the page.
PARAMETER_PROMPT (2):
The response is from [form-filling
prompt][google.cloud.dialogflow.cx.v3.Form.Parameter.fill_behavior]
in the page.
HANDLER_PROMPT (3):
The response is from a [transition
route][google.cloud.dialogflow.cx.v3.TransitionRoute] or an
event handler][EventHandler] in the page or flow or
transition route group.