Volatiles getters are executed even when they are overridden with compose

[Sinled]

Hi, i have strange behaviour with volatile properties, being executed even if they are overriden by next model in compose
here is an example

import { types } from 'mobx-state-tree';

const mixin = types.model({
	name: 'some'
}).volatile(self => {
	return {
		get surname() {
			throw Error('not implemented')
		}
	}
}).views(() => {
	return {
		get fullName() {
			return self.name + self.surname
		}
	}
})

const mixin2 = types.model({}).volatile(self => {
	return {
		surname: 'foo'
	}
})

const Model = types.compose(mixin, mixin2);

console.log(Model.create().fullName);
// ^^ throws `Error: not implemented`

Is this expected behaviour?

With views such approach works fine