comm: Fix sync update prefix initialization

refs: #2399

Change-Id: I35c454e46c0b9552dba2a38b674d1ad3629f8bef
diff --git a/src/communication/sync-logic-handler.cpp b/src/communication/sync-logic-handler.cpp
index 5f87436..94ac76b 100644
--- a/src/communication/sync-logic-handler.cpp
+++ b/src/communication/sync-logic-handler.cpp
@@ -141,9 +141,6 @@
   , m_confParam(conf)
   , m_sequencingManager(seqManager)
 {
-  m_updatePrefix = m_confParam.getLsaPrefix();
-  m_updatePrefix.append(m_confParam.getSiteName());
-  m_updatePrefix.append(m_confParam.getRouterName());
 }
 
 void
@@ -269,6 +266,14 @@
 }
 
 void
+SyncLogicHandler::buildUpdatePrefix()
+{
+  m_updatePrefix = m_confParam.getLsaPrefix();
+  m_updatePrefix.append(m_confParam.getSiteName());
+  m_updatePrefix.append(m_confParam.getRouterName());
+}
+
+void
 SyncLogicHandler::publishSyncUpdate(const ndn::Name& updatePrefix, uint64_t seqNo)
 {
   _LOG_DEBUG("Publishing Sync Update. Prefix: " << updatePrefix << " Seq No: " << seqNo);