[christophilus]

`"hello" + myFooObject.toString()` Can you eliminate that? It's impossible to say without knowing whether or not `myFooObject.toString()` is effectful. Maybe the JVM can make that assessment. Maybe not. I don't know, but it's not as trivial as "knowing what string concatenation does".

[sour-taste]

A straightforward way to do this is for Java to assume built in types like strings are side effect free, but custom types may not be. This would likely cover a good portion of log lines but not all, obviously.