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Yes, Docker / dockerExposedPorts is more specific than Zero / dockerExposedPorts. But unlike what you seem to assume, it's the more specific scopes that delegate to the less specific ones, not the other way around. The manual says so:

This feature allows you to set a value once in a more general scope, allowing multiple more-specific scopes to inherit the value.

And in fact, this is the only way it could be, because you might define e. g. both Docker / dockerExposedPorts and Universal / dockerExposedPorts. Which one of these would Zero / dockerExposedPorts delegate to? There's no sensible answer to that, hence delegation goes in the other direction.