constructor(mimetype, data, filename, filesize) {
        /**
         * MIME type of the attachment
         * @type {string}
         */
        this.mimetype = mimetype;

        /**
         * Base64 encoded data that represents the file
         * @type {string}
         */
        this.data = data;

        /**
         * Document file name. Value can be null
         * @type {?string}
         */
        this.filename = filename;
        
        /**
         * Document file size in bytes. Value can be null
         * @type {?number}
         */
        this.filesize = filesize;
    }
Media attached to a message
@param {string} mimetype MIME type of the attachment
@param {string} data Base64-encoded data of the file
@param {?string} filename Document file name. Value can be null
@param {?number} filesize Document file size in bytes. Value can be null