Compile level Java 7+
Try to Maven compile Java 7+ code containing new Java 7 syntax such as diamond notation: List<String> alist = new ArrayList<>(); or a try-with-resources block
Checkstyle fails with exception EOF expected but found ...
The current Maven Checkstyle version 2.8 in Oscar does not handle the new Java 7 syntax. 2.15 is the minimum version required for Java 7.
Version 3.0* is used with Java 8, but this involves a more complex upgrade. Suggestion is to stick with 2.15 for a while.