Getting updates for read receipts.

SenderReadReceipt.java

//Sender Side
// To listen to an update from all the other channel members' client apps, implement the 'onReadReceiptUpdated()' with things to do when notified.
SendBird.addChannelHandler(UNIQUE_HANDLER_ID, new SendBird.ChannelHandler() {
    @Override
    public void onReadReceiptUpdated(GroupChannel groupChannel) {
        if (currentGroupChannel.getUrl().equals(groupChannel.getUrl())) {
            // For example, code for redrawing a channel view.
        }
    }
});