Easemob\Attachment 成员列表

成员的完整列表，这些成员属于 Easemob\Attachment,包括所有继承而来的类成员

downloadFile($fileName, $uuid, $shareSecret='')	Easemob\Attachment
downloadThumb($fileName, $uuid, $shareSecret='')	Easemob\Attachment
uploadFile($fileName, $restrictAccess=false)	Easemob\Attachment