Snapcraft many changes?

Hello all.
I get errors when using snapcraft 3.0.1

For configflag in parts:

Failed to load plugin: properties failed to load for app: Additional properties are not allowed (‘configflags’ was unexpected)

and for - no-system-libraries in parts:

Issues while validating snapcraft.yaml: The ‘parts/app/build-attributes[1]’ property does not match the required schema: ‘no-system-libraries’ is not one of [‘no-patchelf’, ‘no-install’, ‘debug’, ‘keep-execstack’]

How I can build if I don’t need libs for system?

This property depends on the plugin your part uses, ensure it is supported by the plugin.

I assume this becomes the default behavior of Snapcraft 3 and is no longer needed to be specified now?

Note that you can always fall back to the legacy Snapcraft behavior by not specifying the base key.