Inheritor of openstruct is deserealized to it's base struct

[slavam2605]

I have the following model:

object BuildModel: Ext(IdeRoot) {
  val buildEventModel = openstruct {
    field("id", string)
    field("message", string)
  }

  val startBuildEventModel = structdef extends buildEventModel {
    field("buildDescriptor", buildDescriptorModel)
  }

  val buildDescriptorModel = structdef {
    field("id", string)
    field("title", string)
    field("workingDir", string)
    field("startTime", long)
  }

  init {
    signal("buildEvent", buildEventModel).async
  }
}

I push a StartBuildEventModel to the signal from one side and I get a BuildEventModel on the other side.