title: IntelliJ IDEA 16 can't resolve JDK1.8
body: <p>I have IntelliJ IDEA CE.
  I did some practice coding (had some project in maven) and I was developing it in IDEA 15 CE. Then update came and I cannot build project again, because of error:
  JComboBox usage generified after JDK 1.6 API which would couse compilation problem with JDK 5.0.  (in maven is target JDK 1.8, in IDEA preferences is JDK1.8 and in project preferences is JDK 1.8. I Tried import settings from IDEA 15 (where it still works fine) with no difference,  also I tried clean install IDEA... with no results.
  Any help pls?</p>