No java 8 features (lambdas & co). You can develop & build with jdk8, but don't be tempted to using new goodies. Set your IDE to the jdk7 target, if you are not sure which features this includes. The xmlui won't work with java 8 features, because of old spring mvc and old spring is there to support cocoon. There are few more details in https://jira.duraspace.org/browse/DS-2653. This practice should not be necessary with "new ui", we will reevaluate.