connectionmanager: fix device id

Change-Id: Id006a25ebd5501d143ef7ee1f39008fb1d7cd87e
diff --git a/src/connectionmanager.cpp b/src/connectionmanager.cpp
index 9134bd9..dfe3fec 100644
--- a/src/connectionmanager.cpp
+++ b/src/connectionmanager.cpp
@@ -1783,7 +1783,7 @@
             continue;
         std::map<std::string, std::string> connectionInfo;
         connectionInfo["id"] = callbackIdToString(key.first, key.second);
-        connectionInfo["device"] = key.first;
+        connectionInfo["device"] = key.first.toString();
         if (ci->tls_) {
             if (auto cert = ci->tls_->peerCertificate()) {
                 connectionInfo["peer"] = cert->issuer->getId().toString();