prepend jitsi room names with assembly tag

(to prevent name clashes between assemblies; shared jitsi rooms are
still possible simply by letting their names start with "shared-")

lib/Properties.hs

@@ -154,8 +154,13 @@ checkLayerProperty p@(Property name _value) = case name of
         >>= setProperty "jitsiRoomAdminTag"
         . ("assembly-" <>) -- prepend "assembly-" to avoid namespace clashes
       uselessEmptyLayer
-      unwrapString' p
-        $ suggestProperty $ Property "jitsiTrigger" "onaction"
+      unwrapString p $ \jitsiRoom -> do
+        suggestProperty $ Property "jitsiTrigger" "onaction"
+
+        -- prepend jitsi room names to avoid name clashes
+        unless ("shared-" `isPrefixOf` jitsiRoom) $ do
+          assemblyname <- lintConfig configAssemblyTag
+          setProperty "jitsiRoom" (assemblyname <> "-" <> jitsiRoom)
     "jitsiTrigger" -> do
       isString p
       unlessHasProperty "jitsiTriggerMessage"