FallbackInfo

Information related to how and why a fallback result was used. If this field is set, then it means the server used a different routing mode from your preferred mode as fallback.

JSON representation 
{
  "routingMode": enum (FallbackRoutingMode),
  "reason": enum (FallbackReason)
}
Fields
routingMode

enum (FallbackRoutingMode)

Routing mode used for the response. If fallback was triggered, the mode may be different from routing preference set in the original client request.
reason

enum (FallbackReason)

The reason why fallback response was used instead of the original response. This field is only populated when the fallback mode is triggered and the fallback response is returned.