As Mike Drob pointed out in Solr-8324, many loggers in Solr are unintentionally shared between classes. Many instances of this are caused by overzealous copy-paste. This can make debugging tougher, as messages appear to come from an incorrect location.
As discussed in the comments on
SOLR-8324, there also might be legitimate reasons for sharing loggers between classes. Where any ambiguity exists, these instances shouldn't be touched.