HI, I added JDK 1.8 module for slf4j the purpose is to enable : Call by name (or lazy evaluation) will be accessible using Supplier of String. The example below : logger.trace(() -> "trace msg "+echo()) ; note that echo method and String concatenation will only be evaluation if trace level is enabled. I also initiated the pull request : https://github.com/qos-ch/slf4j/pull/70 Tests are passing on Travis CI. BR.