This class contains simple image closure which allow to put any images from document management system to email template. The syntax is

${image 'picture_1'}. 

'picture_1' is name of document in onCourse system. If onCourse have more than one document with the same name then the first one will be chosen. Make sure that required image has unique name to prevent such collision. The image closure interpreted into simple img html tag like: <img src="https://bucket-ish-oncourse.s3.amazonaws.com/c1ba6238-52f8-43e9-8298-e2bbfc493918?AWSAccessKeyId=NHMUJXKH3BBF6M6QEVOA&Expires=1458561937&Signature=Ej3ittJs7finYguCjnh5WsBhdeD%RR">

 
        public 
        DocumentService
     {
}