title: Why data classes in Kotlin cannot be marked with inner modifier?
body: <p>I have a simple class let's say <code>User</code>. Now I want to create an <code>inner data class</code> let's say <code>UserProperty</code> inside <code>User</code> class, but as soon as I add <code>inner</code> modifier to <code>data</code> class <code>UserProperty</code> the IDE complains about <strong><em>Modifier inner is incompatible with data</em></strong>. What am I missing?</p>