Multiple encodings set for module chunk - "windows-1252" will be used by compiler

Using IDEA 2016.3.4 I get 

Information:java: Multiple encodings set for module chunk <project name> "windows-1252" will be used by compiler

when I try to compile my project. The project contains UTF-8 characters which can't compile. 

Maven compilation for the same project works, as I have set the

<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

I don't know how I can set the encoding for my project, and how there can be multiple encodings for the same project.