If you define logback.debug property to true, then the GafferConfigurator throws exception on line 65.

OnConsoleStatusListener.addNewInstanceToContext(context);

OnConsoleStatusListener.addNewInstanceToContext was removed as part of this commit -> https://github.com/qos-ch/logback/commit/43877e7aa1bba269488682c5925389d37a2102cd#diff-23f59879128a5606f3116f0d989d00f6

This makes it impossible to debug groovy scripts