In fair mode the StandardRotationPolicy re-configures AbstractFetchLimitingMessageSource for a new directory (and possible new ConnectionFactory) in the beforeReceive().
However with default maxFetchSize (or bigger than 1), the receive() would poll toBeReceived internal queue for files cached from the previous polling cycle.
Since we rotate the source immediately to a new set of options, all those cached files don't make sense or even can cause the problem on fetching their content in case of AbstractRemoteFileStreamingMessageSource when we rotate to a new ConnectionFactory.
See more info in the: #8898