Refine implementation of GSM conferences (2/3)

Bug: 17684223

Change-Id: I7a274de891b7efc2a781a16ce7596bf5cd3ea6ff
diff --git a/src/com/android/server/telecom/ConnectionServiceWrapper.java b/src/com/android/server/telecom/ConnectionServiceWrapper.java
index ce93177..cacdc81 100644
--- a/src/com/android/server/telecom/ConnectionServiceWrapper.java
+++ b/src/com/android/server/telecom/ConnectionServiceWrapper.java
@@ -551,7 +551,7 @@
         public void setConferenceableConnections(
                 String callId, List<String> conferenceableCallIds) {
             logIncoming("setConferenceableConnections %s %s", callId, conferenceableCallIds);
-            if (mCallIdMapper.isValidCallId(callId)) {
+            if (mCallIdMapper.isValidCallId(callId) || mCallIdMapper.isValidConferenceId(callId)) {
                 SomeArgs args = SomeArgs.obtain();
                 args.arg1 = callId;
                 args.arg2 = conferenceableCallIds;