This allows a device to identify with different streams, for instance a Lenovo
laptop could have a coreboot firmware or a AMI firmware. The GUIDs would be the
same, but switching firmware would only be done rarely and very carefully.
Another example would be switching the Broadcom BCM57xx nework adaptors from the
vendor nonfree firmware with a signed PXE image, to the free software reverse
engineered driver with no PXE support (and thus no signed DXE) at all.
It is expected firmware would have additional metadata something like this:
...
<branch>sdcc</branch>
<description>
<p>
This is an alternate firmware built by the community using only free
software tools.
</p>
</description>
<requires>
<id compare="ge" version="1.5.0">org.freedesktop.fwupd</id>
<client>switch-branch</client>
</requires>
...
Additionally, alternate branch firmware will not be returned for clients not
setting the FWUPD_FEATURE_FLAG_SWITCH_BRANCH before the GetReleases request.
The idea here is that we can show the user both a string and an optional
line-art image when the update has completed. The line art is often more well
understood for non-English speakers.
