There has been discussion about moving to Java 1.8: #63 - Require Java8, and it was decided to stick with 1.6 because of the needs of our users.

We do not want to be held back by our users for too long, so we should switch to a newer version of Java some day. I propose to switch to the next version when the currently used version has not received public updates for 5 years. For the switch from 1.6 to 1.7, that would mean February 2018 (copied from https://web.archive.org/web/20200616180306/https://en.wikipedia.org/wiki/Java_version_history):

Switching to Java 1.8 would occur in April 2020: https://java.com/en/download/faq/java_7.xml

Now, this does not mean I do not want to support our 1.6 users after February 2018 anymore. They will get support, but can no longer expect that all new features will be available on 1.6. We will have to decide the availability in 1.6 for each feature.

At the switch, the version compatible with 1.6 will be put on a separate branch. This branch will receive bug and security fixes, and features selected to be backported to 1.6. The major version on master can be increased to indicate a backward incompatible change after the split, if desired.