fwiw: slf4j has similar functionality as String.format in terms of nesting things into the string.  You should be able to rewrite this as:
LOG.debug("{} components found in {}, {} expected by row key format. The last {} components implicitly set to null",
            krk, kijiRowKey.toString(), fgc, fgc - krk);

With the amount of processing in your original statement, it's also starting to be worth wrapping it in an isDebug().