[slf4j-user] When more parameters than placeholders, extra parameters are not logged

[jo at durchholz.org]

An additional thought:

Modern JVMs are pretty efficient at building closures.
Log4j2 (not the old log4j version 1) is an alternative where you can replace

   logger.debug("foo is: " + foo)

with

   logger.debug(() -> "foo is: " + foo)

This has the same avoid-constructing-strings logic as

   logger.debug("foo is: {}", foo)

but you don't need to refactor anything.

The downside is that forgetting to create the closure will make logging 
slow, so in the end, you'll likely fall back to the same 
make-sure-everything-is-mass-refactored approach as before, so the 
overall advantage isn't big.
However, you'll get low-hanging fruits faster, at the expense of having 
to try out a different logging framework.

Which means I won't recommend anything, I'm just presenting more choices 
in the hopes that one of them matches your situation better.

Regards,
Jo