Merge pull request #805 from ogis-yamazaki/Avoid_Exceptions_for_persistBufferedMessage

Fix #606

Author: Ranjan Dasgupta

org.eclipse.paho.client.mqttv3/src/main/java-templates/org/eclipse/paho/client/mqttv3/internal/ClientComms.java

@@ -186,7 +186,9 @@ public void sendNoWait(MqttWireMessage message, MqttToken token) throws MqttExce
 				//@TRACE 507=Client Connected, Offline Buffer available, but not empty. Adding message to buffer. message={0}
 				log.fine(CLASS_NAME, methodName, "507", new Object[] {message.getKey()});
 				if(disconnectedMessageBuffer.isPersistBuffer()){
-					this.clientState.persistBufferedMessage(message);
+					if (message instanceof MqttPublish) {
+						this.clientState.persistBufferedMessage(message);
+					}
 				}
 				disconnectedMessageBuffer.putMessage(message, token);
 			} else {