add comment and remove unnecessary fake sync in test case

kong/clustering/services/sync/validate.lua

@@ -32,12 +32,16 @@ local function validate_deltas(deltas, is_full_sync)
       -- validate entity
       local dao = kong.db[delta_type]
       if dao then
-        local ws_id = delta_entity.ws_id  -- bypass ws_id field for validation
-        delta_entity.ws_id = nil
+        -- CP will insert ws_id into the entity, which will be validated as an
+        -- unknown field.
+        -- TODO: On the CP side, remove ws_id from the entity and set it only
+        -- in the delta.
+        local ws_id = delta_entity.ws_id
+        delta_entity.ws_id = nil      -- clear ws_id
 
         local ok, err_t = dao.schema:validate(delta_entity)
 
-        delta_entity.ws_id = ws_id
+        delta_entity.ws_id = ws_id    -- restore ws_id
 
         if not ok then
           errs[#errs + 1] = { [delta_type] = err_t }

kong/db/schema/others/declarative_config.lua

@@ -507,6 +507,9 @@ local function validate_references(self, input)
 end
 
 
+-- TODO: Completely implement validate_references_sync without associating it
+-- to declarative config. Currently, we will use the dc-generated
+-- foreign_references table to accelerate iterating over entity foreign keys.
 function DeclarativeConfig.validate_references_sync(deltas, deltas_map, is_full_sync)
   local errs = {}
 

spec/02-integration/18-hybrid_rpc/06-validate_deltas_spec.lua

@@ -60,7 +60,6 @@ local function setup_bp()
 
   -- init declarative config
   if not cached_dc then
-    kong.sync = "fake sync to generate dc with sync_v2_enabled"
     local err
     cached_dc, err = declarative.new_config(kong.configuration)
     assert(cached_dc, err)