[Treble-Enabled Device Guides, News, & Discussion] albertoduqe:
No expert here but I'd say "repo branch" and "commit" don't mean absolutely anything except that you need to specifiy the repo branch and the specific commit to be applied.

On the other hand I am trying to build a CandyRom GSI following this guide and the spectacular work of phhusson and the rest of the guys making the scripts and project treble possible. I initially modified the build-rom.sh to include candy's repo and run the command. I obviously had a first error because candy.mk didn't exist. Created it and then, as source was there and patches were supposed to have been applied too (although when applying them I get a bunch of errors which I interpret are due to some files that don't exist or code that can't be modified because it doesn't match), opted for the manual building process and run . build/envsetup.sh, lunch treble_arm64_avN-userdebug and make -j8 systemimage. It starts running and then I get a whole bunch of errors before the building begins: missing libraries:

packages/apps/Bluetooth/Android.mk: error: Bluetooth (APPS android-arm64) missing sap-api-java-static (JAVA_LIBRARIES android-arm64)
You can set ALLOW_MISSING_DEPENDENCIES=true in your environment if this is intentional, but that may defer real problems until later in the build.
system/core/adb/Android.mk: error: adbd (EXECUTABLES android-arm64) missing libbootloader_message (STATIC_LIBRARIES android-arm64)
You can set ALLOW_MISSING_DEPENDENCIES=true in your environment if this is intentional, but that may defer real problems until later in the build.
system/core/healthd/Android.mk: error: libhealthd_draw (STATIC_LIBRARIES android-arm64) missing libminui (STATIC_LIBRARIES android-arm64)
You can set ALLOW_MISSING_DEPENDENCIES=true in your environment if this is intentional, but that may defer real problems until later in the build.
system/core/healthd/Android.mk: error: libhealthd_draw (STATIC_LIBRARIES android-arm) missing libminui (STATIC_LIBRARIES android-arm)
You can set ALLOW_MISSING_DEPENDENCIES=true in your environment if this is intentional, but that may defer real problems until later in the build.
system/core/healthd/Android.mk: error: libhealthd_charger (STATIC_LIBRARIES android-arm64) missing libminui (STATIC_LIBRARIES android-arm64)
You can set ALLOW_MISSING_DEPENDENCIES=true in your environment if this is intentional, but that may defer real problems until later in the build.
system/core/healthd/Android.mk: error: libhealthd_charger (STATIC_LIBRARIES android-arm) missing libminui (STATIC_LIBRARIES android-arm)
You can set ALLOW_MISSING_DEPENDENCIES=true in your environment if this is intentional, but that may defer real problems until later in the build.
system/core/healthd/Android.mk: error: charger (EXECUTABLES android-arm64) missing libminui (STATIC_LIBRARIES android-arm64)
You can set ALLOW_MISSING_DEPENDENCIES=true in your environment if this is intentional, but that may defer real problems until later in the build.
system/core/init/Android.mk: error: init (EXECUTABLES android-arm64) missing libbootloader_message (STATIC_LIBRARIES android-arm64)
You can set ALLOW_MISSING_DEPENDENCIES=true in your environment if this is intentional, but that may defer real problems until later in the build.
system/extras/slideshow/Android.mk: error: slideshow (EXECUTABLES android-arm64) missing libminui (STATIC_LIBRARIES android-arm64)
You can set ALLOW_MISSING_DEPENDENCIES=true in your environment if this is intentional, but that may defer real problems until later in the build.
system/vold/Android.mk: error: libvold (STATIC_LIBRARIES android-arm64) missing libbootloader_message (STATIC_LIBRARIES android-arm64)
You can set ALLOW_MISSING_DEPENDENCIES=true in your environment if this is intentional, but that may defer real problems until later in the build.
system/vold/Android.mk: error: libvold (STATIC_LIBRARIES android-arm) missing libbootloader_message (STATIC_LIBRARIES android-arm)
You can set ALLOW_MISSING_DEPENDENCIES=true in your environment if this is intentional, but that may defer real problems until later in the build.
system/vold/Android.mk: error: vold (EXECUTABLES android-arm64) missing libbootloader_message (STATIC_LIBRARIES android-arm64)
You can set ALLOW_MISSING_DEPENDENCIES=true in your environment if this is intentional, but that may defer real problems until later in the build.
system/vold/Android.mk: error: libminivold (STATIC_LIBRARIES android-arm64) missing libbootloader_message (STATIC_LIBRARIES android-arm64)
You can set ALLOW_MISSING_DEPENDENCIES=true in your environment if this is intentional, but that may defer real problems until later in the build.
system/vold/Android.mk: error: libminivold (STATIC_LIBRARIES android-arm) missing libbootloader_message (STATIC_LIBRARIES android-arm)
You can set ALLOW_MISSING_DEPENDENCIES=true in your environment if this is intentional, but that may defer real problems until later in the build.
system/vold/Android.mk: error: minivold (RECOVERY_EXECUTABLES android-arm64) missing libbootloader_message (STATIC_LIBRARIES android-arm64)
You can set ALLOW_MISSING_DEPENDENCIES=true in your environment if this is intentional, but that may defer real problems until later in the build.
vendor/candy/charger/Android.mk: error: libhealthd.candy (STATIC_LIBRARIES android-arm64) missing libminui (STATIC_LIBRARIES android-arm64)
You can set ALLOW_MISSING_DEPENDENCIES=true in your environment if this is intentional, but that may defer real problems until later in the build.
vendor/candy/charger/Android.mk: error: libhealthd.candy (STATIC_LIBRARIES android-arm) missing libminui (STATIC_LIBRARIES android-arm)
You can set ALLOW_MISSING_DEPENDENCIES=true in your environment if this is intentional, but that may defer real problems until later in the build.
build/core/main.mk:798: error: exiting from previous errors.
09:08:01 ckati failed with: exit status 1

I have built and used Candy for lithium and never had any building errors, so I have no idea why those libraries are missing or of course how to fix it...

If anyone can give a hint it will be appreciated.

Thanks and keep it up!