Swift_Mime_SimpleMimeEntity | --Swift_Mime_Attachment | --Swift_Mime_EmbeddedFile
Located in File: /vendors/swiftMailer/classes/Swift/Mime/EmbeddedFile.php
Overridden in child classes as:
Overrides : Swift_Mime_Attachment::__construct() Create a new Attachment with $headers, $encoder and $cache.
Overrides : Swift_Mime_Attachment::getNestingLevel() Get the nesting level used for this attachment.
Returns LEVEL_RELATED.