- Mapbox SDK version: 2.1.1

I want to spawn randomly some trees inside a specific feature (in this case landuse / park). I am using the mechanism of the GameObjectModifiers->SpawnInsideModifier. So far so good as you can see in the image below.
But i need to avoid spawning trees in the water. As those layers seems to be separated i'm in trouble creating a featuremodifier which handles this case.
how could i achieve this ?
best regards and thanks in advance