Determines if the given Throwable is considered a permanent error that
indicates a message cannot be retried. A permanent error indicates an
error in configuration, message data, application logic, etc. that does
not change over short periods of time.
SAF calls this method whenever message delivery fails. This could be during
conversation startup, or while sending a conversation message after setup.
If this method returns true, SAF will not attempt to retry sending this
message, and it will be rejected. Appropriate error handling (via
SAFEndpointManager/SAFErrorAwareEndpointManager will be performed on the