diagnosing onException problem?

[Freeman, Keith]

I have this code in my route:

        onException(Exception.class)
                .handled(true)

                .maximumRedeliveries(-1)
                .redeliveryDelay(1L * 1000L)
                .backOffMultiplier(2.0D)
                .maximumRedeliveryDelay(60L * 1000L)

                .logRetryAttempted(true)
                .retryAttemptedLogLevel(LoggingLevel.WARN)
                .logRetryStackTrace(true)

                .logStackTrace(true)
                .log(LoggingLevel.ERROR,
                        ConfiguredRouteBuilder.class.getSimpleName() +
": onException handler: caught Exception! ${property." +
Exchange.EXCEPTION_CAUGHT + "}")


But when an exception happens, the delay between retries is always 1
second (or whatever I change the redeliveryDelay number to), there's
never any backoff (the retry logs are always 1-second apart).  So 2
questions:

1- why isn't the backoff multiplier having any effect?
2- is there a way (short of stepping through Camel source code) for me
to diagnose something like this?

(I'm on camel 2.12.1)