Parses an imeta tag into a MediaAttachment, or returns null if the
tag is not a valid encrypted-media-v1 attachment.
A null result means the media reference is invalid and MUST be dropped (the
containing message should be dropped too for a host-safety failure). See
decodeMediaImetaTag for the exact conditions.
Parses an
imetatag into a MediaAttachment, or returnsnullif the tag is not a validencrypted-media-v1attachment.A
nullresult means the media reference is invalid and MUST be dropped (the containing message should be dropped too for a host-safety failure). See decodeMediaImetaTag for the exact conditions.