I have a maven project forked and cloned from a git repo onto my eclipse. It is build on Java 8. The first thing i do is perform a
mvn clean install
In my case, it was caused from an incompatibility with OpenJDK 9 (which I haven't investigated).
If you don't need JDK 9, a temporary work-around would be to purge it from your machine:
sudo apt-get remove --purge openjdk-9-jdk openjdk-9-jre
sudo apt-get remove --purge openjdk-9-jdk-headless openjdk-9-jre-headless