This is mostly to help others facing the same issue, as we just spent 4x3 hours figuring this out.
An app, that consumes syslog entries and forwards JMS (over OpenMQ), was upgraded from camel 2.13.0 to 2.14.0.
Afterwards many things broke upstream, which was masked by poor logging in some Glassfish servers (truncating stacktraces).
Turns out that the CamelSyslogTimestamp header was silently discarded, being a java.util.GregorianCalendar instance.
Forcing it into a java.util.Date before routing to the JMS endpoint restored service throughout the valuechain.
As I wrote; this is mostly a FYI to others .
But perhaps the documentation might reflect the lack of guaranteed conversion?