This is a refactor to current JSON logging to make it more open for extensions
and support for custom ES log messages used inDeprecationLogger IndexingSlowLog , SearchSLowLog
We want to include x-opaque-id in deprecation logs. The easiest way to have this as an additional JSON field instead of part of the message is to create a custom DeprecatedMessage (extends ESLogMEssage)
These messages are regular log4j messages with a text, but also carry a map of fields which can then populate the log pattern. The logic for this lives in ESJsonLayout and ESMessageFieldConverter.
Similar approach can be used to refactor IndexingSlowLog and SearchSlowLog JSON logs to contain fields previously only present as escaped JSON string in a message field.
closes#41350
backport #41354
e23ecc5838