The documentation lists the following
asynchronous - Determines if the primitive will be created asynchronously or block until ready. If false initializeTerrainHeights() must be called first.
but for initializeTerrainHeights the following is stated
Initializes the minimum and maximum terrain heights. This only needs to be called if you are creating the GroundPrimitive asynchronously.
The two statements seem to conflict,
which is it?