refactor(emqx_config): check if upgrade_raw_conf is exported

apps/emqx/src/emqx_config.erl

@@ -325,7 +325,7 @@ init_load(SchemaMod, Conf) when is_list(Conf) orelse is_binary(Conf) ->
     ok = save_schema_mod_and_names(SchemaMod),
     HasDeprecatedFile = has_deprecated_file(),
     RawConf0 = load_config_files(HasDeprecatedFile, Conf),
-    RawConf1 = apply(SchemaMod, upgrade_raw_conf, [RawConf0]),
+    RawConf1 = upgrade_raw_conf(SchemaMod, RawConf0),
     warning_deprecated_root_key(RawConf1),
     RawConf2 =
         case HasDeprecatedFile of
@@ -342,6 +342,14 @@ init_load(SchemaMod, Conf) when is_list(Conf) orelse is_binary(Conf) ->
     maybe_init_default_zone(),
     ok.
 
+upgrade_raw_conf(SchemaMod, RawConf) ->
+    case erlang:function_exported(SchemaMod, upgrade_raw_conf, 1) of
+        true ->
+            SchemaMod:upgrade_raw_conf(RawConf);
+        false ->
+            RawConf
+    end.
+
 %% Merge environment variable overrides on top, then merge with overrides.
 overlay_v0(SchemaMod, RawConf) when is_map(RawConf) ->
     RawConfWithEnvs = merge_envs(SchemaMod, RawConf),

apps/emqx/src/emqx_schema.erl

@@ -174,7 +174,6 @@
 -export([password_converter/2, bin_str_converter/2]).
 -export([authz_fields/0]).
 -export([sc/2, map/2]).
--export([upgrade_raw_conf/1]).
 
 -elvis([{elvis_style, god_modules, disable}]).
 
@@ -183,10 +182,6 @@
 -define(DEFAULT_MULTIPLIER, 1.5).
 -define(DEFAULT_BACKOFF, 0.75).
 
-%% dummy callback from eqmx_config:init_load
-upgrade_raw_conf(RawConf) ->
-    RawConf.
-
 namespace() -> broker.
 
 tags() ->