Fix compilation error in TbWebSocketHandlerTest

Author: MazurenkoNick

application/src/test/java/org/thingsboard/server/controller/plugin/TbWebSocketHandlerTest.java

@@ -42,6 +42,7 @@
 import org.thingsboard.server.service.security.model.UserPrincipal;
 import org.thingsboard.server.service.ws.WebSocketService;
 import org.thingsboard.server.service.ws.WebSocketSessionRef;
+import org.thingsboard.server.service.ws.WebSocketSessionType;
 
 import java.io.IOException;
 import java.lang.reflect.Method;