Logging

Logging level should be applied according to following rules:

• INFO - system messages
• DEBUG - logging of request and response related parameters/fields. Also some important flow messages.
• TRACE - verbose logging for deep debugging.
• ERROR - is for internal error, e.g. exception occurred or something wrong with logic.
• WARN - system warning, e.g. keys are about to expire.

Goal is to control how noisy logging is depending on log level.