Hello Norman I checked this package (ibsmlnj-smlnj) in Debian testings (upcoming Bullseye) and still contains the files you mention and that triggers this false positive.
I believe that chkrootkit's nature is very trigger-happy and i tend to consider this behaviour more like a feature rater than a bug. As a workaround: Once you checked *carefully* all this files and dirs, i suggest to put this dir names in an exclude file. I don't feel that this should be done in the package as it is posible to exclude some suspicious files that every sysadmin should inspect closely. if the thread doesn't get any more responses, i will close this bug in a few days. Greetings, Marcos