I have a content type AbstractType defined like this:

<attribute name="link" type="content" contentType="content-type.AbstractType"/>
<property name="label" path="title"/>

And another type FinalType extending AbstractType with this:

<property name="label" path="libelle"/>

From a content of type FinalType I call:

content.getValue("label")

or

content.getValue("link/label", true)

and I obtain the value contained in the "libelle" attribute.

But if I do:

content.dataToJSON(view)

with a view referencing link / label. I obtain the value contained in the "title" attribute.