See https://cwiki.apache.org/confluence/display/KAFKA/KIP-449%3A+Add+connector+contexts+to+Connect+worker+logs
Added LoggingContext as a simple mechanism to set and unset Mapped Diagnostic Contexts (MDC) in the loggers to provide for each thread useful parameters that can be used within the logging configuration. MDC avoids having to modify lots of log statements, since the parameters are available to all log statements issued by the thread, no matter what class makes those calls.
The design intentionally minimizes the number of changes to any existing classes, and does not use Java 8 features so it can be easily backported if desired, although per this KIP it will be applied initially only in AK 2.3 and later and must be enabled via the Log4J configuration.
Reviewers: Jason Gustafson <jason@conflent.io>, Guozhang Wang <wangguoz@gmail.com>