lambda expressions cannot be parsed by ecj/janino

Using Java8 lambda expression in the decision template like

bean1.call(() -> $param);

you will run into compiler issues with ejc as well as the currently supported version of JANINO (2.5.16). I tried to manually upgrade the JANINO compiler version, but got stuck in compatibility issues as the Scanner seems to have been changed regarding exception handling.

Can you suggest to fix the incompatibility with JANINO > 2.5.16 such that lambda expressions can be parsed by the newest parsers? Would be nice