Structured logging

[cosmin-marginean]

Hi. I wanted to know how structured logging can be used efficiently and what scenario it's targeting. The example in the readme is not a valid one and doesn't even compile because the message string uses a variable - I assumed this is an attempt to read something from the payload, but probably missing the right pattern for that field?

Is this to support structured (JSON, for example) logging when the underlying log implementation supports that? Or is the payload used simply to format the log message?