anchor.diff:  		
   		if (username != null)
   			message['username'] = username;
  +		
  +		if (channel != null)
  +			message['channel'] = channel;
   		
   		if (icon_url != null)
   			message['icon_url'] = icon_url;
  
positive.code: 	String username;
  	
  	/**
  	 * By default, the message will show an icon that looks like the webhooks icon. You can change this by setting [icon_url] or [icon_emoji]
  	 **/
  	String icon_url;
  
negative.code:     /**
  	 * Creates an [Message] object which can be sent to a Slack channel
  	 **/
  	Message(this.text, {this.username,this.channel,this.icon_emoji,this.icon_url,this.attachments});
    
  	/**
  	 * Prints out the [Map] that this object represents
  