Add failure to RespondNexusTaskFailedRequest

Author: pdoerner

temporal/api/workflowservice/v1/request_response.proto

@@ -1829,8 +1829,10 @@ message RespondNexusTaskFailedRequest {
     string identity = 2;
     // A unique identifier for this task.
     bytes task_token = 3;
-    // The error the handler failed with.
-    temporal.api.nexus.v1.HandlerError error = 4;
+    // Deprecated. Use the failure field instead.
+    temporal.api.nexus.v1.HandlerError error = 4 [deprecated = true];
+    // The error the handler failed with. Must contain a NexusHandlerFailureInfo object.
+    temporal.api.failure.v1.Failure failure = 5;
 }
 
 message RespondNexusTaskFailedResponse {