public String getRejectionMessage() {
        return rejectionMessage;
    }
Returns 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 none was defined. If no text was
specified then no message will be sent to the parties of the rejected file transfer.

@return the text to include in a message that will be sent to the parties of the file
transfer that got rejected or {@code null} if none was defined.
xmppserver/src/main/java/org/jivesoftware/openfire/filetransfer/FileTransferRejectedException.java