Document reset_history_event_id (#419)

Document reset_history_event_id

Author: Quinn-With-Two-Ns

openapi/openapiv2.json

@@ -7166,7 +7166,8 @@
         },
         "resetHistoryEventId": {
           "type": "string",
-          "format": "int64"
+          "format": "int64",
+          "description": "If non zero, indicates the server has discarded the workflow task that was being responded to.\nWill be the event ID of the last workflow task started event in the history before the new workflow task.\nServer is only expected to discard a workflow task if it could not have modified the workflow state."
         }
       }
     },

temporal/api/workflowservice/v1/request_response.proto

@@ -357,7 +357,9 @@ message RespondWorkflowTaskCompletedResponse {
     PollWorkflowTaskQueueResponse workflow_task = 1;
     // See `ScheduleActivityTaskCommandAttributes::request_start`
     repeated PollActivityTaskQueueResponse activity_tasks = 2;
-
+    // If non zero, indicates the server has discarded the workflow task that was being responded to.
+    // Will be the event ID of the last workflow task started event in the history before the new workflow task.
+    // Server is only expected to discard a workflow task if it could not have modified the workflow state.
     int64 reset_history_event_id = 3;
 }