Cannot resolve method .isEmpty()

Hello, im struggling with this issue. Was coding my web application typed 2 times .isEmpty() but when i did it 3rd time it was red(none of method is working) and show this error. Whole application was working. Past methods i typed are working.  Cant also use || in  if. Without new methods application seems working. In other project everything is ok. now i realize that something is wrong with maven libraries .

Things i tried so far and didnt work:

Invalidate cache/restart

Add once more sdk

Delete sdk and install 

Reimport maven 

Inteliij Ultimate 2018.2.5

Java 8 191