Log4J: Log entry formats

Log4J supports mysterious patterns to control each log entry output, for example:

%date{yyyy-MM-dd'T'HH:mm:ss.SSSZ} %-5level --- [%thread] %class{1} %msg%n%throwable`

They are documented here:

https://logging.apache.org/log4j/2.x/manual/layouts.html#pattern-layout