Syslog (both RFC-3164 and 5424) use newline characters to frame messages. As Log4J2 messages may include newlines in the message body, it is necessary to replace newlines with a configurable escape string.
I've implemented a configuration option "newLineEscape" which accepts a replacement string. The default is to not escape newlines (i.e. current behavior).
I've also implemented a configuration option "exceptionConverstion", which accepts the same options as PatternLayout's %exception field. If no value is specified, exceptions are not included.