Make `Mask` execution strict about nullable booleans #3697

Job	Run time
check-java-publish-build (x86_64-unknown-linux-gnu, runs-on=27609863792/runner=amd64-medium/image...	47s
Rust publish dry-run	20s
Python (wheel build)	5m 25s
check-java-publish-build (aarch64-unknown-linux-gnu, runs-on=27609863792/runner=arm64-medium/imag...	54s
Compat check / compat-test	3m 0s
	10m 26s

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