Optimizing FB schema:

* Replaced Response union with nullable fields
* "Ok" code replaced with a boolean and a separate structure for a error code and message.
* Inlined geometry, thus removing one layer of indirection.

include/engine/api/flatbuffers/fbresult.fbs

@@ -6,17 +6,18 @@ include "trip.fbs";
 
 namespace osrm.engine.api.fbresult;
 
-union ServiceResponse {
-    match: Match,
-    nearest: Nearest,
-    route: Route,
-    table: Table,
-    trip: Trip
+table Error {
+    code: string;
+    message: string;
 }
 
 table FBResult {
-    code: string;
-    message: string;
+    error: bool = false;
+    code: Error;
     data_version: string;
-    response: ServiceResponse;
+    match: Match;
+    nearest: Nearest;
+    route: Route;
+    table: Table;
+    trip: Trip;
 }

include/engine/api/flatbuffers/route.fbs

@@ -70,16 +70,11 @@ table Intersection {
     lanes: [Lane];
 }
 
-table Geometry {
-    polyline: string;
-    polyline6: string;
-    coordinates: [Position];
-}
-
 table Step {
     distance: double;
     duration: double;
-    geometry: Geometry;
+    polyline: string;
+    coordinates: [Position];
     weight: double;
     name: string;
     ref: string;
@@ -109,7 +104,8 @@ table RouteObject {
     weight: double;
     weight_name: string;
     confidence: double; //Used only by 'Match' service
-    geometry: Geometry;
+    polyline: string;
+    coordinates: [Position];
     legs: [Leg];
 }