Update: actually I now discovered the bug in my `@...

# squarelibraries

[Lukasz Kalnik]

Update: actually I now discovered the bug in my @ToJson implementation: I was using toJson() instead of toJsonValue(). That's why the serialized JSON was escaped like a plain string. It didn't have anything to do with nesting.
But I will switch to a polymorphic adapter factory anyway, because then I won't have to implement from/to JSON functions myself and won't be able to make these kind of errors.