fix unit test

Author: dmytro-landiak

application/src/test/java/org/thingsboard/mqtt/broker/actors/device/PersistedDeviceActorMessageProcessorTest.java

@@ -337,6 +337,7 @@ public void givenDevicePublishMsg_whenChannelNonWritable_thenStopProcessing() {
 
     @Test
     public void givenDevicePublishMsg_whenMessageIsNotExpired_thenProcessingIsCorrect() {
+        persistedDeviceActorMessageProcessor.setSessionCtx(mock(ClientSessionCtx.class));
         MqttProperties properties = new MqttProperties();
         properties.add(new MqttProperties.IntegerProperty(BrokerConstants.PUB_EXPIRY_INTERVAL_PROP_ID, 100));