cleanup: conversations for conference

Change-Id: Iea6d39916b46158f4438a95e6de5350b00e0a0f0

src/api/conversationmodel.h

@@ -107,7 +107,7 @@ public:
      * @param  search name filter
      * @return filtered conversations
      */
-    std::map<ConferenceableItem, ConferenceableValue> getConferenceableConversations(std::string convId, std::string filter = {}) const;
+    std::map<ConferenceableItem, ConferenceableValue> getConferenceableConversations(const std::string& convId, const std::string& filter = {}) const;
     /**
      * Get a custom filtered set of conversations
      * @return conversations filtered

src/conversationmodel.cpp

@@ -362,7 +362,7 @@ ConversationModel::allFilteredConversations() const
 }
 
 std::map<ConferenceableItem, ConferenceableValue>
-ConversationModel::getConferenceableConversations(std::string convId, std::string filter) const
+ConversationModel::getConferenceableConversations(const std::string& convId, const std::string& filter) const
 {
     auto conversationIdx = pimpl_->indexOf(convId);
     if (conversationIdx == -1 || !owner.enabled) {