From d653ba0ffafd0fd49abc3596a7f4ddb687fddc56 Mon Sep 17 00:00:00 2001
From: Janusz Jakubiec <januszjakubiec@MacBook-Pro-administrator.local>
Date: Wed, 27 Oct 2021 09:29:37 +0200
Subject: [PATCH] Fixing mod_roster_backend to allow optional callbacks

---
 src/mod_roster_backend.erl | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/mod_roster_backend.erl b/src/mod_roster_backend.erl
index 51d5c55117e..c609600a112 100644
--- a/src/mod_roster_backend.erl
+++ b/src/mod_roster_backend.erl
@@ -124,4 +124,9 @@ remove_user_t(HostType, LUser, LServer) ->
 -spec remove_domain_t(mongooseim:host_type(), jid:lserver()) -> ok.
 remove_domain_t(HostType, LServer) ->
     Args = [HostType, LServer],
-    mongoose_backend:call(HostType, ?MAIN_MODULE, ?FUNCTION_NAME, Args).
+    case mongoose_backend:is_exported(HostType, ?MAIN_MODULE, ?FUNCTION_NAME, 2) of
+        true ->
+            mongoose_backend:call(HostType, ?MAIN_MODULE, ?FUNCTION_NAME, Args);
+        false ->
+            ok
+    end.