Unsupported Java Language Version warning

On one of the projects I was trying to generate test for, I got a warning about Java 6 not being supported:
But I checked the JDK version of the module and project and it looks like they are correctly using java 8:

Is there something else I need to configure?
I get some tests generated anyway so its not a big issue, but I wonder if that could cause any problems.

Here is a view of the event log:

Can you also check the settings under “Project”? I guess that the language level is set to 6 there.
As far as I know, Cover does support generating tests for code written and compiled for older Java versions, but it it generally assumes that you are using Java 8 or later, so generating tests for Java 6 is best-effort.