https://issues.apache.org/jira/browse/LOG4J2-455
When AsyncLogger received log message (method public void log(final Marker marker, final String fqcn, final Level level, final Message data, final Throwable t)), currently it uses clock.currentTimeMillis() (see at Line 221) as the timestamp. But it should check the message implements TimestampMessage or not, if yes, should use TimestampMessage.getTimestamp() as the timestamp, if not , then using clock.currentTimeMillis(). The new Code: *data instanceof TimestampMessage ? ((TimestampMessage) data ).getTimestamp() : clock.currentTimeMillis();*
