gistfile1.java

@Embeddable
class Address {
    ...
    @Convert(...) private String city;
}


@Entity
@Convert(attributeName="homeAddress.city", disableConversion=true)
class Person {
    ...
    private Address homeAddress;
}

gistfile2.xml

<entity class="Person">
    <attributes>
        <embedded name="homeAddress">
            <convert attributeName="city" .../>
        </embedded>
    </attributes>
</entity>