public void setRejectionMessage(String rejectionMessage) {
        this.rejectionMessage = rejectionMessage;
    }
Sets the text to include in a message that will be sent to the initiator and target of the
file transfer that got rejected or {@code null} if no message will be sent to the parties
of the rejected file transfer. Bt default, no message will be sent.

@param rejectionMessage the text to include in the notification message for the rejection.
xmppserver/src/main/java/org/jivesoftware/openfire/filetransfer/FileTransferRejectedException.java